HELP ME ASAP! Will give BRAINLIEST! Please read the question THEN answer correctly! No guessing. Check ALL that apply.
Answers
Answer:
-2 & 1/3
Step-by-step explanation:
When you set the two equations equal to each other, they form to parallel, vertical lines. They cross the x-axis at -2 and 1/3. Hope this helps.
Related Questions
1.4.2 Suppose a car dealership offers a low interest rate and a longer payoff period to customers or a high interest rate and a shorter payoff period to customers, and most customers choose the low interest rate and longer payoff period, does that mean that most customers want a lower interest rate? Explain.
Answers
Answer:
Yes, customers that deal on cars
But no, if not car customers.
Step-by-step explanation:
Most customers of cars want lower interest rate because it gives them opportunity to work for a longer period and gradually make the profit and pay back.
Even if it will take time that was why the dealer made it longer time.
But this might not apply to customer to other services because they might have their own principles or government/policies or interest rate to their customers.
what is this phrase in numerical expression
triple the sum of seventeen and ten
pls help
Answers
Answer: so you would do 17 plus ten which is 27 so triple 3 so your answer is 27^3
Step-by-step explanation:
sum so your adding plus you need the exponent which is times 3
The management of Discount Furniture, a chain of discount furniture stores in the Northeast, designed an incentive plan for salespeople. To evaluate this innovative plan, 12 salespeople were selected at random, and their weekly incomes before and after the plan were recorded. Was there a significant increase in the typical salesperson’s weekly income due to the innovative incentive plan? Use the .05 significance level. Estimate the p-value, and interpret it
Answers
Answer:
Step-by-step explanation:
The question is incomplete. The complete question is
The management of Discount Furniture, a chain of discount furniture stores in the Northeast, designed an incentive plan for salespeople. To evaluate this innovative plan, 12 salespeople were selected at random, and their weekly incomes before and after the plan were recorded.
Salesperson Before After
Sid Mahone $320 $340
Carol Quick 290 285
Tom Jackson 421 475
Andy Jones 510 510
Jean Sloan 210 210
Jack Walker 402 500
Peg Mancuso 625 631
Anita Loma 560 560
John Cuso 360 365
Carl Utz 431 431
A. S. Kushner 506 525
Fern Lawton 505 619
Solution:
Corresponding income of salespersons before and after form matched pairs.
The data for the test are the differences between the income is salespersons.
μd = the income before minus their income after.
Bedore after diff
320 340 -20
290 285 5
421 475 - 54
510 510 0
210 210 0
402 500 - 98
625 631 -6
569 560 0
360 365 - 5
431 431 0
506 525 - 19
505 619 - 114
Sample mean, xd
= (- 20 + 5 - 54 + 0 + 0 - 98 - 6 + 0 - 5 + 0 + - 19 - 114)/12 = - 25.92
xd = - 25.92
Standard deviation = √(summation(x - mean)²/n
n = 12
Summation(x - mean)² = (- 20 + 25.92)^2 + (5 - 25.92)^2 + (- 54 + 25.92)^2+ (0 + 25.92)^2 + (0 + 25.92)^2 + ( - 98 + 25.92)^2 + ( - 6 + 25.92)^2 + (0 + 25.92)^2 + (- 5 + 25.92)^2 + (0 + 25.92)^2 + (- 19 + 25.92)^2 + (- 114 + 25.92)^2 = 17784.5168
Standard deviation = √(17784.5168/12
sd = 38.5
For the null hypothesis
H0: μd ≥ 0
For the alternative hypothesis
H1: μd < 0
1) The distribution is a students t. Therefore, degree of freedom, df = n - 1 = 12 - 1 = 11
2) The formula for determining the test statistic is
t = (xd - μd)/(sd/√n)
t = ( - 25.92- 0)/(38.5/√12)
t = - 2.33
3) We would determine the probability value by using the t test calculator.
p = 0.02
4) Assume alpha = 0.05
Since alpha, 0.05 > than the p value, 0.02, then we would reject the null hypothesis. We can conclude that at 5% significance level, there is a significant increase in the typical salesperson’s weekly income due to the innovative incentive plan
A sphere is inscribed in a cube. Explain the relationship between the surface areas of the two solid figures
Answers
Answer:
No one knows. Jk just go look at the other brainly links. the question has already been asked and answered so you can go see them there.
Step-by-step explanation:
:)
If u(x)=-2x^2+3 and v(x)=1/x, what is the range of (uov)(x)
Answers
Answer:
Do my question i will do yours
Step-by-step explanation:
Answer:
The Answer is C
Step-by-step explanation:
100 POINTS
PLEASE PROVIDE STEPS. FOR BOTH
FIND THE INTEGRALS
Answers
Answer:
8. -⅓ cos³x + C
9. sec x + eˣ + C
Step-by-step explanation:
8. ∫ sin x cos²x dx
If u = cos x, then du = -sin x dx.
∫ -u² du
-⅓ u³ + C
-⅓ cos³x + C
9. ∫ (sec x tan x + eˣ) dx
∫ sec x tan x dx + ∫ eˣ dx
These are both standard integrals:
sec x + eˣ + C
Question 8:
∫sinxcos²xdx
∫-u²du (let u = cos(x))
-∫u²du
-u(^2+1)/2+1
-cos^(2+1)(x)/2+1
-1/3cos³(x)
-1/3cos³(x) + C
Question 9:
∫(secxtanx + eˣ)dx
∫sec(x)tan(x)dx + ∫eˣdx (apply sum rule)
sec(x) + eˣ (sec(x)tan(x)dx = sec(x) and eˣdx = eˣ)
sec(x) + eˣ + C
Best of Luck!
€1.4 m
1.9 m
Tim has to cover 3 tanks completely with paint.
Each tank is in the shape of a cylinder with a top and a bottom.
The tank has a diameter of 1.4 metres and a height of 1.9 m.
A tin of paint covers 5 m
Find the total surface area of the 3 tanks and state how
many tins of paint Tim will need to buy
You must show your working
Total marks 5
Answers
Answer:
Step-by-step explanation:
Since each tank is cylindrical, we would apply the formula for determining the total surface area of a cylinder which is expressed as
Total surface area = 2πr² + 2πrh
Where
r represents the height of the cylinder.
h represents the height of the cylinder.
π = 3.14
From the information given,
Height = 1.9
Diameter = 1.4
Radius = diameter/2 = 1.4/2 = 0.7
Total surface area = 2 × 3.14 × 0.7² + 2 × 3.14 × 0.7 × 1.9 = 3.0772 + 8.3524 = 11.4296 m²
Total surface area of the 3 cylinders = 11.4296 × 3 = 34.29 m²
Since a tin of paint covers 5 m², the number of tins paints that Tim will need to buy is
34.29/5 = 6.858
Since the tins of paint must be whole numbers, he needs to buy 7 tins of paints.
The circle graph shows how Spencer spent his money in the month of July.
A circle graph representing Spencers expenses. 27 percent is clothing, 11 percent is Gasoline, 44 percent is Food and 18 percent is Entertainment.
Part A
If Spencer spent a total of $704.00 in the month of July, which is the best estimate for the amount of money he spent on clothing?
$70.00
$140.00
$210.00
$280.00
00:00
Part B
Which is the best estimate for the amount of money he spent on entertainment?
$140.00
$35.00
$105.00
$160.00
Answers
Answer:
$190.08
Step-by-step explanation:
Take 27% of the total $704 spent in July:
0.27($704) = $190.08
He spent an estimated $190.08 on clothing in July.
Answer:
Step-by-step explanation:
I THINK 140
Round 299 to the nearest hundred. Enter your answer in the box below.
Answers
Answer:
300
Step-by-step explanation:
hundreds tens ones
2 9 9
We look at the tens
It is 5 or higher so we round up the hundreds place
2 becomes 3
300
Answer:
300
Step-by-step explanation:
its obv 300 because 299 is greater than 249 and if it is less than 249 it is rounded to 200.
In the past, 19% of all homes with a stay-at-home parent had the father as the stay-at-home parent. An independent research firm has been charged with conducting a sample survey to obtain more current information. (a) What sample size is needed if the research firm's goal is to estimate the current proportion of homes with a stay-at-home parent in which the father is the stay-at-home parent with a margin of error of 0.03? Use a 95% confidence level. (Round your answer up to the nearest whole number.)
Answers
Answer:
A sample size of 657 is needed.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.
[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]
In which
z is the zscore that has a pvalue of [tex]1 - \frac{\alpha}{2}[/tex].
The margin of error is:
[tex]M = z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]
95% confidence level
So [tex]\alpha = 0.05[/tex], z is the value of Z that has a pvalue of [tex]1 - \frac{0.05}{2} = 0.975[/tex], so [tex]Z = 1.96[/tex].
In the past, 19% of all homes with a stay-at-home parent had the father as the stay-at-home parent.
This means that [tex]\pi = 0.19[/tex]
(a) What sample size is needed if the research firm's goal is to estimate the current proportion of homes with a stay-at-home parent in which the father is the stay-at-home parent with a margin of error of 0.03?
A sample size of n is needed.
n is found when [tex]M = 0.03[/tex]
Then
[tex]M = z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]
[tex]0.03 = 1.96\sqrt{\frac{0.19*0.81}{n}}[/tex]
[tex]0.03\sqrt{n} = 1.96\sqrt{0.19*0.81}[/tex]
[tex]\sqrt{n} = \frac{1.96\sqrt{0.19*0.81}}{0.03}[/tex]
[tex](\sqrt{n})^{2} = (\frac{1.96\sqrt{0.19*0.81}}{0.03})^{2}[/tex]
[tex]n = 656.91[/tex]
Rounding up to the nearest whole number.
A sample size of 657 is needed.
What is the formula to find the area of a circle?
Answers
Answer:
A= [tex]\pi[/tex]r²
Step-by-step explanation:
the area of a circle
What is the volume of a cylinder with a base radius of 4 and height 7?
Answers
Answer:
351.86
Step-by-step explanation:
Suppose the probability of an athlete taking a certain illegal steroid is 10%. A test has been developed to detect this type of steroid and will yield either a positive or negative result. Given that the athlete has taken this steroid, the probability of a positive test result is 0.995. Given that the athlete has not taken this steroid, the probability of a negative test result is 0.992. Given that a positive test result has been observed for an athlete, what is the probability that they have taken this steroid
Answers
Answer:
93.25% probability that they have taken this steroid
Step-by-step explanation:
Bayes Theorem:
Two events, A and B.
[tex]P(B|A) = \frac{P(B)*P(A|B)}{P(A)}[/tex]
In which P(B|A) is the probability of B happening when A has happened and P(A|B) is the probability of A happening when B has happened.
In this question:
Event A: Positive test
Event B: Taking the steroid.
Suppose the probability of an athlete taking a certain illegal steroid is 10%.
This means that [tex]P(B) = 0.1[/tex]
Given that the athlete has taken this steroid, the probability of a positive test result is 0.995.
This means that [tex]P(A|B) = 0.995[/tex]
Positive test:
99.5% of 10%(If the athlete has taken).
100-99.2 = 0.8% of 100-10 = 90%(Athlete has not taken)
Then
[tex]P(B) = 0.995*0.1 + 0.008*0.9 = 0.1067[/tex]
Given that a positive test result has been observed for an athlete, what is the probability that they have taken this steroid
[tex]P(B|A) = \frac{P(B)*P(A|B)}{P(A)} = \frac{0.1*0.995}{0.1067} = 0.9325[/tex]
93.25% probability that they have taken this steroid
The Sears Tower, at 1,451 feet, is one of the tallest structures in the United States. A penny is thrown from the top of the tower. The height, h, of the penny is recorded after each second, t, in the table. Write an equation for the curve of best fit, then find the approximate height of the penny after 7 seconds.
Answers
Answer:
The equation for the height of the penny in function of time is:
[tex]h(t)=1451-16t^2[/tex]
After 7 seconds, the penny will be at a height of 667 feet.
Step-by-step explanation:
The penny will have a free fall.
The initial velocity is zero, and the initial height is h(0)=1,451.
The acceleration will be the gravity, that has a value g=32 ft/s^2.
Then, we can model this starting by the speed:
[tex]dv/dt=-g\\\\v(t)=v_0-gt=-gt[/tex]
Then, the height becomes:
[tex]dh/dt=v(t)=-gt\\\\h(t)=h_0-\dfrac{gt^2}{2}=1451-\dfrac{32}{2}t^2\\\\\\h(t)=1451-16t^2[/tex]
The approximate height of the penny after 7 seconds can be calculated as:
[tex]h(7)=1451-16(7^2)=1451-16*49=1451-784=667[/tex]
After 7 seconds, the penny will be at a height of 667 feet.
You roll two dice. How many ways can you
roll a sum of 8 or a sum of 10?
Answers
Answer:
5 different ways
Step-by-step explanation:
for the 8
2 and 6
3 and 5
4 and 4
for then tens
5 and 5
4 and 6
Angle of rotation :(((
Answers
Answer:
144
Step-by-step explanation:
360/5 x 2 = 144
6.SP.2 Understand that a set of data collected to answer a statistical question has a distribution which can be described by its
center, spread, and overall shape.
6.SP.3 Recognize that a measure of center for a numerical data set summarizes all of its values with a single number, while a
measure of variation describes how its values vary with a single number.
6.SP.4 Display numerical data in plots on a number line, including dot plots, histograms, and box plots.
TASK: You are an employee at a small company. In this company, there are 10 employees who make
$15,000/yr, one manager who makes $100,000/yr, and one CEO who makes $2,000,000/yr. An
employee complained about the salaries to the Department of Labor and the company was brought
under investigation. The CEO responded to the Department of Labor saying:
"The average salary in my company is $187,500. There is no need for concern."
The Data
Employee 2
Employee 3
Employee 4
Employee 5
Employee 6
Employee 1
$15,000
$15,000
$15,000
$15,000
$15,000
$15,000
Employee 7
Employee 8
Employee 9
Employee 10
Manager
CEO
$15,000
$15,000
$15,000
$15,000
$100,000
$2,000,000
Day 1
I.
Which measure of central tendency did the CEO use to describe his company's salaries? (Mean,
Median, Mode)
Was the CEO telling the truth? Explain.
Was the CEO's response a fair description of what is happening in the company?
II.
II.
Answers
If you didn’t know my brush the pool
Trisomy 18 (T18) is a rare genetic disorder that severely disrupts a baby's development prior to birth. Many die before birth and most die before their first birthday. T18 occurs in only 1 in 2500 pregnancies in the U.S. A genetic test on the mother's blood can be done to test for T18 in her baby. The overall probability of a positive test result is 0.010384. The probability of a positive test result for a baby with T18 is 0.97. The probability of a negative test result for a baby without T18 is 0.99. A mother's blood tests positive for T18. What is the probability that her baby has T18
Answers
Answer:
3.74% probability that her baby has T18
Step-by-step explanation:
Bayes Theorem:
Two events, A and B.
[tex]P(B|A) = \frac{P(B)*P(A|B)}{P(A)}[/tex]
In which P(B|A) is the probability of B happening when A has happened and P(A|B) is the probability of A happening when B has happened.
In this question:
Event A: Positive test.
Event B: The baby having T18.
T18 occurs in only 1 in 2500 pregnancies in the U.S.
This means that [tex]P(B) = \frac{1}{2500} = 0.0004[/tex]
The probability of a positive test result for a baby with T18 is 0.97.
This means that [tex]P(A|B) = 0.97[/tex]
The overall probability of a positive test result is 0.010384.
This means that [tex]P(A) = 0.010384[/tex]
What is the probability that her baby has T18
[tex]P(B|A) = \frac{0.0004*0.97}{0.010384} = 0.0374[/tex]
3.74% probability that her baby has T18
What goes into the boxes
Answers
Answer:
See explanation
Step-by-step explanation:
[tex]6 {c}^{2} + 2 {c}^{4} - c \\ \\ standard \: form = \red{ \boxed{ \bold{2 {c}^{4} + 6 {c}^{2} - c}}} \\ \\ degree = \purple{ \boxed{ \bold{4}}} \\ \\ leading \: coefficient = \orange{ \boxed{ \bold{1}}}[/tex]
State if the two vectors are parallel, orthogonal, or neither.
u=18i+8j
v=9i+4j
Answers
Answer:
Parallel, since [tex]\vec u = 2\cdot \vec v[/tex].
Step-by-step explanation:
The relation between both vectors is determined by the use of the dot product, whose expression is:
[tex]\cos \theta = \frac{\vec u \bullet \vec v}{\|\vec u\| \|\vec v\|}[/tex]
Where:
[tex]\cos \theta = 1[/tex] if vectors are parallel to each other and [tex]\cos \theta = 0[/tex] if vectors are orthogonal. Then, norms and dot product are calculated hereafter:
[tex]\|\vec u\| = \sqrt{18^{2}+8^{2}}[/tex]
[tex]\|\vec u\| \approx 19.698[/tex]
[tex]\|\vec v \| = \sqrt{9^{2}+4^{2}}[/tex]
[tex]\|\vec v\| \approx 9.849[/tex]
[tex]\vec u \bullet \vec v = (18)\cdot (9) + (8)\cdot (4)[/tex]
[tex]\vec u \bullet \vec v = 194[/tex]
[tex]\cos \theta = \frac{194}{(19.698)\cdot (9.849)}[/tex]
[tex]\cos \theta = 1[/tex]
The two vectors are parallel to each other, which is also supported by the fact that one vector is multiply of the other one. That is,
[tex]18i + 8j = 2\cdot (9i + 4j)[/tex]
[tex]\vec u = 2\cdot \vec v[/tex]
Consider the graph of the exponential function, y =3(2)^x. The x- intercept of the graph is
Answers
Answer:
the x intercept is 2
Step-by-step explanation:
I just went over this unit
Answer:
2
Step-by-step explanation:
Which statements are true? Check all that apply.
A: StartRoot 1.8 EndRoot < 1.8
B: StartRoot 1.8 EndRoot greater-than 1
C: StartRoot 1.8 EndRoot less-than StartRoot 1.9 EndRoot
D: 1.3 less-than StartRoot 1.8 EndRoot less-than 1.4
E: StartRoot 1.9 EndRoot + StartRoot 1.8 EndRoot greater-than 2
F: StartRoot 1.9 EndRoot minus StartRoot 1.8 EndRoot greater-than 0.1
Answers
Answer:
The answer is all of them except the last one so... A,B,C,D,E.
Step-by-step explanation:
To indicate that we want both the positive and the negative square root of a radicand we put the symbol ± (read as plus minus) in front of the root. Zero has one square root which is 0. Negative numbers don't have real square roots since a square is either positive or 0.
Answer:
A,B,C,D,and E
Step-by-step explanation:
4. The Gold family sold their house for $450,000. They paid a realty
company 6% for selling the house. How much money did they pay the
company? *
Answers
Answer:
27,000
Step-by-step explanation:
$450,000 x 0.06= $27,000
0.06 is the 6% that you multiply by the total amount they earned to see how much they paid the realty company.
Writing Percents as Fractions
a. Write 35% as a fraction in simplest form.
35% =
35
100
Write as a fraction with
a denominator of 100.
7
20
Simplity.
Answers
Answer:
Answers are below
Step-by-step explanation:
Percent means "out of 100" so 35% is 35/100. We can simplify this fraction by dividing the numerator and denominator by 5. 35/100 / 5 = 7/20.
7/20 multiply the numerator and denominator by 5.
7/20 x 5 = 35/100
If this answer is correct, please make me Brainliest!
Answer:
b and c
Step-by-step explanation:
Priscilla’s grandmother’s fruit salad recipe calls for one part apple, one part orange, four parts strawberry, two parts cherry, and three parts grape. Priscilla uses the same measuring cup to measure all of the fruit, so one part is equal to one cup of diced fruit. In this exercise, you will compare the quantities in the recipe to understand ratios better.
Answers
Answer:
There are 11 parts of fruit: 4-strawberry, 3- grape, 2, cherry, 1- apple, 1-orange 4/11 from the entine quantity of fruits- strawberry
3/11-grapes
2/11- cherries
1/11- apples
1/11- oranges } ⇒ the quantity of oranges and apples are equal Hope it helps ;>
1a. Find the set of possible and actual zeros according to the rational root theorem using f(x)=3x^3+13x^2+16x+4
1b. Zeros Multiplicity Cross/Turn
|____|_________|_________|
|____|_________|_________|
c. End Behavior:
d. Y-int:
e. Graph.
2. Divide using synthetic Division: x^4-6x^2-2/x-2
3. Diving Using Long Division: 3x^3+5x^2+4x+1/3x+2
4. Using synthetic division and the remainder theorem to find P(c) if P(x)=4x^3+6x^2+4x+3 and c=-1
5. Use synthetic division and the given factor to completely factor each polynomial function and find the zeros: y=x^3+6x^2+3x-10;(x-1)
Factored Form:
Zeros:
Answers
Answer:.....
Step-by-step explanation:
......
what is the value of the rational expression below when x is equal to 4? x+20/x+4
Answers
Answer:
3
Step-by-step explanation:
All we need to do here is plug in the number 4 for the variable x. Wherever there's an x, kidnap it and replace it with a 4!
[tex]\frac{x + 20}{x + 4}[/tex]
x = 4
[tex]\frac{4 + 20}{4 + 4}[/tex]
Do the addition.
4 + 20 = 24
4 + 4 = 8
[tex]\frac{24}{8}[/tex]
We can simplify this! What is 24 divided by 8?
24/8 = 3
The answer is 3!
A grocery store has an average sales of $8000 per day. The store introduced several advertising campaigns in order to increase sales. To determine whether or not the advertising campaigns have been effective in increasing sales, a sample of 64 days of sales was selected. It was found that the average was $8300 per day. From past information, it is known that the standard deviation of the population is $1200. The p-value is
Answers
Answer:
The p-value of the test is 0.023.
Step-by-step explanation:
In this case we need to determine whether the addition of several advertising campaigns increased the sales or not.
The hypothesis can be defined as follows:
H₀: The stores average sales is $8000 per day, i.e. μ = 8000.
Hₐ: The stores average sales is more than $8000 per day, i.e. μ > 8000.
The information provided is:
[tex]n=64\\\bar x=\$8300\\\sigma=\$1200[/tex]
As the population standard deviation is provided, we will use a z-test for single mean.
Compute the test statistic value as follows:
[tex]z=\frac{\bar x-\mu}{\sigma/\sqrt{n}}=\frac{8300-8000}{1200/\sqrt{64}}=2[/tex]
The test statistic value is 2.
Decision rule:
If the p-value of the test is less than the significance level then the null hypothesis will be rejected.
Compute the p-value for the two-tailed test as follows:
[tex]p-value=P(Z>2)\\=1-P(Z<2)\\=1-0.97725\\=0.02275\\\approx 0.023[/tex]
*Use a z-table for the probability.
The p-value of the test is 0.023.
John wants to invest P dollars at a 4% interest rate. After 5 years the investment will be worth 2000 dollars. How much will it be worth in 11 years?
Answers
Answer:
About $2530.63
Step-by-step explanation:
The formula for this kind of calculation is [tex]A=P(1+\frac{r}{n})^{nt}[/tex], where P is the initial investment, r is the interest rate, n is the number of times you compound your investment per year, and t is the number of years. Assuming that you compound yearly, plugging in the numbers that you have given, you are left with:
[tex]2000=P(1+\frac{0.04}{1})^{t}[/tex]
[tex]2000=P\cdot (1.04)^5\\P\approx 1643.85\\A=1643.85 \cdot (1.04)^{11}\approx $2530.63[/tex]
Hope this helps!
Three methods, A, B and C, are available for teaching a certain industrial skill. The failure rate is 15% for A, 5% for B and 10% for C. The method A is used 30%, B is used 40% and C is used 30% of the time. A worker is taught the skill by one of the methods but fails to learn it correctly. a. (10 points) What is the probability that he was taught by method A? b. (5 points) What is the probability of B given A?
Answers
Answer:
a) so the correct answer is that the probability that method A has been taught is 0.4737
b) the probability that B receives A is 0.5
Step-by-step explanation:
With the previous data we know that 3 methods teach an industrial skill and when putting into practice a worker does not learn, we have the failure rates like this:
method A fails 15%
method B fails: 5%
method C fails: 10%
usage percentages:
A: 30%
B: 40%
C: 30%
a) the probability that method A has been taught is as follows:
P (failure rate) = P (A) * P (failure rate A) + P (B) * P (failure rate B) + P (C) * P (failure rate C)
we replace the data obtaining:
P = 0.3 * 0.15 + 0.4 * 0.05 + 0.3 * 0.1 = 0.095
P ( failure rate A) = P (A) * P (failure rate A) / P (failure rate)
we replace the data obtaining:
0.3 * 0.15 / 0.095 = 0.4737
so the correct answer is that the probability that method A has been taught is 0.4737
b) the probability that B receives A is as follows:
P (B | A) = P (B) = 0.50
