Many people consider their smart phone to be essential! Communication, news, Internet, entertainment, photos, and just keeping current are all conveniently possible with a smart phone. However, the battery better be charged or the phone is useless. Battery life of course depends on the frequency, duration, and type of use. One study involving heavy use of the phones showed the mean of the battery life to be 15.25 hours with a standard deviation of 2.2 hours. Then the battery needs to be recharged. Assume the battery life between charges is normally distributed.

Required:
a. Find the probability that with heavy use, the battery life exceeds 11 hours.
b. You are planning your recharging schedule so that the probability your phone will die is no more than 5%. After how many hours should you plan to recharge your phone?

Answer:

9.9 hours

Step-by-step explanation:

The formula to determine the time together is

1/a+1/b = 1/c  where a and b are the times alone and c is the time together

1/18 + 1/22 = 1/c

The least common multiply of the denominators is 198c

198c(1/18 + 1/22 = 1/c)

11c+ 9c = 198

20c = 198

Divide by 20

20c/20 =198/20

c =9.9

Answer:

B - 9.9 hrs

Step-by-step explanation:

took the test.

i think this could be the answer

Answer:

Question to number 6 is-3

Question to number 7 is 3

Question to number 8 is 2 to the second power

Step-by-step explanation:

please correct me if I’m wrong and for number 8 I am correct it’s just I didn’t know how to put the little 2 on top of the big one

Step-by-step explanation:

question 6 is - 3

question 7 is 3

question 8 is 4

hi

9x750 = 630 +450= 1080 ml

so 1.08 liter.

Answer:

Option B

Step-by-step explanation:

x<-3 means the values of x will be less than -3, do the dot will be blank and towards the left side of -3

Answer:

x = 34

Step-by-step explanation:

Pytago:

x[tex]30^{2} + 16^{2} = x^2\\x = \sqrt{30^2 + 16^2} \\x = 34[/tex]

Answer:

C. 1 and 2

Step-by-step explantation:

First, i would order them as U>T, T>R, R>Q, S>T

we can rewrite them as

U>T>R>Q,

now adding S, we get U>S>T>R>Q,

so U>S

We can also rewrite all of them as inequalities:

U-T>0

T-R>0

R-Q>0

S-T>0

Add R-Q and T-R

(R-Q)+(T-R)>0

-Q+T>0

T>Q, but because S>T we can say S>Q

Answer:

Permutation. ; 83810 ways

Step-by-step explanation:

Permutation and combination methods refers to mathematical solution to finding the number of ways of making selection for a group of objects.

Usually, selection process whereby the order of selection does not matter are being treated using permutation, while those which takes the order of selection into cognizance are calculated using combination.

Here, selecting 2 members (president and vice president) from 290 ; since order of arrangement does not matter, we use permutation ;

Recall :

nPr = n! ÷ (n - r)!

Hence,

290P2 = 290! ÷ (290 - 2)!

290P2 = 290! ÷ 288!

290P2 = (290 * 289) = 83810 ways

A circle is a curve sketched out by a point moving in a plane. The measure of a is 70°. The correct option is B.

A circle is a curve sketched out by a point moving in a plane so that its distance from a given point is constant; alternatively, it is the shape formed by all points in a plane that are at a set distance from a given point, the centre.

In the given circle, the line AC is the diameter of the circle, therefore, the measure of ∠ABC will be 90°.

∠ABC = 90°

This is because a triangle formed on the diameter of the circle such that all the vertices of the triangle intersect the circle, then the angle opposite to the diameter is a right angle.

Now, in ΔABC, the sum of all the angles of the triangle can be written as,

∠ABC + ∠BCA + ∠BAC = 180°

90° + a + 20° = 180°

110° + a = 180°

a = 180° - 110°

a = 70°

Hence, the measure of a is 70°.

Learn more about Circle:

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Answer:

that is n standard notation mah frand

8.9 × 10^3 being scientific notation of " 8900 "

[tex]\huge\text{Hey there!}[/tex]

[tex]\large\textsf{8.9}\times\large\textsf{10}^\mathsf{3}\\\\\mathsf{10^3}\\\mathsf{= 10\times10\times10}\\\mathsf{= 100\times10}\\\mathsf{= \bf 1,000}\\\\\large\textsf{8.9}\times\large\textsf{1,000}\\\\\large\textsf{= \bf 8,900}\\\\\\\boxed{\boxed{\huge\text{Answer: \boxed{\underline{\underline{\bf 8,900}}}}}}\huge\checkmark[/tex]

[tex]\huge\text{Good luck on your assignment \& enjoy your day!}[/tex]

~[tex]\boxed{\huge\text{}\boxed{\frak{Amphitrite1040:)}}}[/tex]

Answer:

100

Step-by-step explanation:

well you can put 5 students in each class guaranteed 5 times over so it would make sense because 5 for each class 9th-12th 5 times over again and again will eventually give you the answer of 100 5•20

If we take 5 students are in each class.

Then let minimum number of students be x

ATQ

1/20()x = 5

x = 5 × 20

x = 100

Answer: 100 people

Must click thanks and mark brainliest

Answer:

[tex]x = 12[/tex]

Step-by-step explanation:

Given

[tex]\angle D = 9x + 5[/tex]

[tex]\angle F = 13x -43[/tex]

Required

Find x

To find x, we make use of:

[tex]\angle D =\angle F[/tex] --- opposite angles of a parallelogram

So, we have:

[tex]9x + 5 =13x -43[/tex]

Collect like terms

[tex]9x - 13x = -5-43[/tex]

[tex]-4x = -48[/tex]

Divide by -4

[tex]x = 12[/tex]

The given line is orthogonal to the plane you want to find, so the tangent vector of this line can be used as the normal vector for the plane.

The tangent vector for the line is

d/dt (⟨0, 9, 6⟩ + ⟨7, -7, -6⟩t ) = ⟨7, -7, -6⟩

Then the plane that passes through the origin with this as its normal vector has equation

⟨x, y, z⟩ • ⟨7, -7, -6⟩ = 0

We want the plane to pass through the point (9, 6, 0), so we just translate every vector pointing to the plane itself by adding ⟨9, 6, 0⟩,

(⟨x, y, z⟩ - ⟨9, 6, 0⟩) • ⟨7, -7, -6⟩ = 0

Simplifying this expression and writing it standard form gives

⟨x - 9, y - 6, z⟩ • ⟨7, -7, -6⟩ = 0

7 (x - 9) - 7 (y - 6) - 6z = 0

7x - 63 - 7y + 42 - 6z = 0

7x - 7y - 6z = 21

so that

a = 7, b = -7, c = -6, and d = 21

An equation of the plane orthogonal to the line 7x - 7y - 6z = 21.

The given line is orthogonal to the plane you want to find,

So the tangent vector of this line can be used as

The normal vector for the plane.

The tangent vector for the line is,

A tangent vector is a vector that is tangent to a curve or surface at a given point.

d/dt (⟨0, 9, 6⟩ + ⟨7, -7, -6⟩t ) = ⟨7, -7, -6⟩

Then the plane that passes through the origin with this as its normal vector has the equation

⟨x, y, z⟩ • ⟨7, -7, -6⟩ = 0

We want the plane to pass through the point (9, 6, 0), so we just

translate every vector pointing to the plane itself by adding ⟨9, 6, 0⟩,

(⟨x, y, z⟩ - ⟨9, 6, 0⟩) • ⟨7, -7, -6⟩ = 0

Simplifying this expression and writing it in standard form gives

⟨x - 9, y - 6, z⟩ • ⟨7, -7, -6⟩ = 0

7 (x - 9) - 7 (y - 6) - 6z = 0

7x - 63 - 7y + 42 - 6z = 0

7x - 7y - 6z = 21

So that, a = 7, b = -7, c = -6, and d = 21.

To learn more about the equation of plane visit:

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Answer:

The fourth number line is the answer.

Step-by-step explanation:

[tex] - 18 > - 5x + 2 \geqslant - 48 \\ ( - 18 - 2) > - 5x \geqslant ( - 48 - 2) \\ - 20 > - 5x \geqslant - 50 \\ \\ \frac{ - 20}{ - 5} > x \geqslant \frac{ - 50}{ - 5} \\ \\ 4 > x \geqslant 10[/tex]

Answer:

Step-by-step explanation:

The mode is the correct answer

Answer:

[tex](x,y) = (1,2)[/tex] -------- [tex]R_{y-axis}[/tex]

[tex](x,y)=(2,-1)[/tex] --------- [tex]R_{y=x}[/tex]

Step-by-step explanation:

Given

[tex](x,y) = (-1,2)[/tex]

Required

[tex]R_{y-axis}[/tex]

[tex]R_{y=x}[/tex]

[tex]R_{y-axis}[/tex] implies that:

[tex](x,y) = (-x,y)[/tex]

So, we have: (-1,2) becomes

[tex](x,y) = (1,2)[/tex]

[tex]R_{y=x}[/tex] implies that

[tex](x,y) = (y,x)[/tex]

So, we have: (-1,2) becomes

[tex](x,y)=(2,-1)[/tex]

Answer:

34.88

Step-by-step explanation:

I took the test

The distance between the building and the ladder is 34.88 foot, the correct option is B.

A triangle in which one of the angle measure is equal to 90 degree is called a right triangle.

The ladder forms a right triangle with the building and the ground,

The length of the triangle is 40 foot

The angle made by the ladder is 29.32 degree

By using Trigonometric Ratios

cos 29.32 = Base /  Hypotenuse

cos 29.32 = Base / 40

Base is the distance between the building and the ladder.

Base = 34.88 foot

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Answer: x = 45

Step-by-step explanation:

Given

(2/3)x + 4 = (4/5)x - 2

Add 2 on both sides

(2/3)x + 4 + 2 = (4/5)x - 2 + 2

(2/3)x + 6 = (4/5)x

Subtract (2/3)x on both sides

(2/3)x + 6 - (2/3)x = (4/5)x - (2/3)x

6 = (12/15)x - (10/15)x

6 = (2/15)x

Divide 2/15 on both sides

6 / (2/15) = (2/15)x / (2/15)

[tex]\boxed{x=45}[/tex]

Hope this helps!! :)

Please let me know if you have any questions

Answer:

x = 45

Step-by-step explanation:

2/3 x + 4 = 4/5x - 2             Add 2 to both sides

2/3 x + 4 + 2 = 4/5x            Combine

2/3x + 6 = 4/5x                   Subtract 2/3 x from both sides.

6 = 4/5x - 2/3 x                  Multiply both sides by 15

6*15 = 4/5 x * 15 - 2/3x * 15

6*15 = 12x - 10x                   Combine the left and right

90 = 2x                               Divide by 2

x = 45

Let's see if it works.

LHS = 2/3 * 45 + 4

LHS = 2*15 + 4

LHS = 30 + 4

LHS = 34

RHS

Right hand side = 4/5 * 45 - 2

RHS = 36 - 2

RHS = 34 which is the same as the LHS

9514 1404 393

Answer:

  24

Step-by-step explanation:

The front face is an 8-sided star, so has 8 edges. We presume the back face is the same, so it also has 8 edges. Each of the front vertices is connected by an edge to each of the corresponding back vertices, so there are 8 more edges connecting front and back.

The total number of edges is 8 + 8 + 8 = 24.

9514 1404 393

Answer:

  118

Step-by-step explanation:

Oganesson is the heaviest element ever created. It is a "super-heavy" noble gas with a half-life less than 1 millisecond. Its atomic number is 118.

Multiplying a matrix by a scalar results in every entry in a matrix get multiplied by that scalar, as defined,

[tex]a\begin{bmatrix}b&c\\d&e\\\end{bmatrix}=\begin{bmatrix}ab&ac\\ad&ae\\\end{bmatrix}[/tex]

So in our case, ([tex]0.2=\frac{1}{5}[/tex]

[tex]\frac{1}{5}\begin{bmatrix}50&10\\25&15\\\end{bmatrix}=\begin{bmatrix}\frac{50}{5}&\frac{10}{5}\\\frac{25}{5}&\frac{15}{5}\\\end{bmatrix}=\boxed{\begin{bmatrix}10&2\\5&3\\\end{bmatrix}}[/tex]

Hope this helps :)

Answer:

0.8015

Step-by-step explanation:

Hope I'm correct lol

Answer:

One solution

BRAINLIEST, PLEASE!

Step-by-step explanation:

2y - x = 6

2y = x + 6

y = x/2 + 3

y = 2x + 7

After graphing, they have one solution at (-2.667, 1.667).

Answer:

3 +4 i

Step-by-step explanation:

x + sqrt(yz)

Let x = 3 y=2  and z = -8

3 + sqrt(2*-8)

3+ sqrt(-16)

3 + sqrt(16) sqrt(-1)

We know sqrt(-1) = i

3 +4 i

Answer:

The p-value of the test is 0.0228, which is less than the standard significance level of 0.05, which means that there is evidence that the proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced.

Step-by-step explanation:

Before solving this question, we need to understand the central limit theorem and subtraction of normal variables.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean [tex]\mu = p[/tex] and standard deviation [tex]s = \sqrt{\frac{p(1-p)}{n}}[/tex]

Subtraction between normal variables:

When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

1999:

20 out of 100 in the bottom third, so:

[tex]p_1 = \frac{20}{100} = 0.2[/tex]

[tex]s_1 = \sqrt{\frac{0.2*0.8}{100}} = 0.04[/tex]

2001:

10 out of 100 in the bottom third, so:

[tex]p_2 = \frac{10}{100} = 0.1[/tex]

[tex]s_2 = \sqrt{\frac{0.1*0.9}{100}} = 0.03[/tex]

Test if proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced.

At the null hypothesis, we test if the proportion is still the same, that is, the subtraction of the proportions in 1999 and 2001 is 0, so:

[tex]H_0: p_1 - p_2 = 0[/tex]

At the alternative hypothesis, we test if the proportion has been reduced, that is, the subtraction of the proportion in 1999 by the proportion in 2001 is positive. So:

[tex]H_1: p_1 - p_2 > 0[/tex]

The test statistic is:

[tex]z = \frac{X - \mu}{s}[/tex]

In which X is the sample mean, [tex]\mu[/tex] is the value tested at the null hypothesis, and s is the standard error.

0 is tested at the null hypothesis:

This means that [tex]\mu = 0[/tex]

From the two samples:

[tex]X = p_1 - p_2 = 0.2 - 0.1 = 0.1[/tex]

[tex]s = \sqrt{s_1^2 + s_2^2} = \sqrt{0.04^2 + 0.03^2} = 0.05[/tex]

Value of the test statistic:

[tex]z = \frac{X - \mu}{s}[/tex]

[tex]z = \frac{0.1 - 0}{0.05}[/tex]

[tex]z = 2[/tex]

P-value of the test and decision:

The p-value of the test is the probability of finding a difference of at least 0.1, which is the p-value of z = 2.

Looking at the z-table, the p-value of z = 2 is 0.9772.

1 - 0.9772 = 0.0228.

The p-value of the test is 0.0228, which is less than the standard significance level of 0.05, which means that there is evidence that the proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced.

Answer:

Because it's a negative.

Step-by-step explanation:

The value of a positive number is still a positive number.

Answer:

A is correct.

x>5 means all numbers greater than BUT not equal to 5.

The open circle means "not equal".

So,  A is correct.

Hope this helps!

Answer:

Graph A.

Step-by-step explanation:

Answer: x > 5 means all x values greater than 5

thus, the graph that best shows that x is greater than 5 is graph A.

Explanation: because x isn't being itself I mean by x isn't just 5 but greater than 5 (graph a)

graph b shows x being less than 5 which is wrong

graph c shows x being greater than 5 but being equal to 5 because of the bold circle

graph d shows everything wrong about x. first it's not suppose to be less than and second x isn't equal to 5

therefore the answer graph A.

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doomdabomb: all brainliest and thanks are appreciated

and would mean a lot to me, thanks!