For initial 100 milligrams of a radioactive substance was if decreased by 2% in 8 hours, then half-life of the radioactive substance is 108.3 hours.
Rate of change is the change in one variable due to change in other.
Given the following:
Amount of a radioactive substance initially present=100mg
After 8 hours, mass decreased by 2%
Mass after 8 hours= 100-(2% of 100)
=100-(2*100/100)
=100-2
=98
The rate of decay is proportional to the amount of the substance present at time t.
Mathematically,
Let the amount of radioactive substance is A and at time t,
[tex]\dfrac d{dt}A\ \alpha\ A\\\\[/tex]
[tex]\dfrac d{dt}A= kA\\\\\\dA=kAdt[/tex]
On integrating both sides,
[tex]\int \frac {1}{kA}dA=\int dt\\\\[/tex]
[tex]\dfrac {ln A}{k}=t +ln \ c_1\\ln A =kt+k\ ln \ c_1\\[/tex]
On taking antilogarithm both sides,
[tex]e^{ln A} =e^{kt+k\ ln \ c_1\\A=e^{kt}e^{k\ ln \ c_1}\\A=e^{kt}e^{\ ln \ c_1^k}\\A=e^{kt}c_1^k \\[/tex]
Let, [tex]c_1^k=c[/tex]
[tex]A =e^{kt}c[/tex].................................1
At t=0, A=100
Substituting values in 1
[tex]100= e^0c\\c=100[/tex]
At t= 8, A=98
[tex]98=e^{k8}100\\0.98=e^{8k}\\8k=ln0.98[/tex]
k=-0.0064.
To determine the half time of the decay.
At half time A became A/2=50 mg
Substituting in 1.
[tex]50=e^{-0.0064t}100\\ln 0.5=-0.0064t\\t=\frac{ln 0.5}{-0.0064}\\t=108.3042\\t=108.3[/tex]....................................rounded to one decimal place.
Thus, The half-life of the radioactive substance is 108.3 hr.
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how do i solve for
(2x/5)+1=13/5
Answer:
x = 4
Step-by-step explanation:
[tex]\frac{2x}{5} +1 = \frac{13}{5}[/tex] [tex]\frac{2x+5}{5} = \frac{13}{5}[/tex] divide both sides by 52x + 5 = 13 subtract 5 from both sides2x = 8 divide both sides by 2x = 4
h(x)=6/(x-3), find h(5)
h(5) means the value of h(x) at x = 5. So what we have to do is to substitute x = 5 in the function.
We are given the function h(x) below:
[tex] \large{h(x) = \frac{6}{x - 3} }[/tex]
Substitute x = 5 in the equation.
[tex] \large{h(5) = \frac{6}{5 - 3} \longrightarrow \frac{6}{2} }[/tex]
Simplify in the simplest form.
[tex] \large{h(5) = \frac{3}{1} \longrightarrow 3}[/tex]
Thus h(5) is 3.
Answer
h(5) = 3Hope this helps! Let me know if you have any doubts.
Weather it’s true or false?
given triangle abc is similar to triangle efg, with medians cd and gh respectively, ac=9, eg=6, cd=x+2, gh=2x-4. find the length of cd
Answer:
X= 9//
Step-by-step explanation:
abc = efg
ac + cd = eg + gh
9 + (x+2) = 6 + (2x-4)
9 - 6 = 2x-4 - (x+2)
3 = x - 6
3+6 = x
9 = x//
if sin (A+B)=1 and tan (A-B)=1/sqroot 3
are acute angles. find out the value of A and B
Answer:
A = 60° , B = 30°
Step-by-step explanation:
[tex]sin(A+B ) = 1\\\\\ \ \ (A + B) \ = \ \ sin^{-1} 1\\\\A + B = 90^\circ --(1)\\\\ \ tan (A - B) = \frac{1}{\sqrt{3}}\\\\(A-B) = tan^{-1}\frac{1}{\sqrt3}}\\\\A - B = 30^\circ --(2)\\\\ (1) + (2) => 2A = 120^\circ\\[/tex]
[tex]A = 60^\circ[/tex]
[tex]from \ (1) \\A + B = 90^\circ\\60^\circ + B = 90^\circ\\B = 90^\circ - 60^\circ\\B = 30^\circ[/tex]
The triangles shown below must be congruent.
10
80°
10
810
81
A. True
B. False
Answer:
It is TRUE
When two triangles are congruent they will have exactly the same three sides and exactly the same three angles
PLS MARK BRAINLIEST
The ratio of men to women at a meeting is 7:6.If there are 28 men at the meeting;
a. How many women are at the meeting?
b. How many men and women are at the meeting?
Answer:
a. 24 woman
b. 28 men and 24 women
Step-by-step explanation:
a.
given: men to women = 7:6
find: number of women
solution: 28 / 7 = 4, 4 * 6 = 24 women
b.
given: number of men
find: number of men and women
solution: 28 men and 24 women
hope this helps....
Answer:
A) 24 women
B) 52 men and women are at the meeting
Step-by-step explanation:
A)
Let y = women at the meeting
7:6 = 28:y
7/6 = 28/y
6×38 = 7y
6×28⁴/7¹ = 7y¹/7¹
y= 6×24
y=24
B)
Number of women at the meeting = 24
Number of men at the meeting = 28
Total number of people at the meeting = 24+28
= 52
please help!!
A city has a population of 220,000 people. Suppose that each year the population grows by 8.75%. What will the population be after 13 years?
Use the calculator provided and round your answer to the nearest whole number.
Answer:
P = 660,592
Step-by-step explanation:
p = [tex]222,000 (1+.0875)^{t}[/tex]
P = [tex]222,000 (1+.0875)^{13}[/tex]
P = 660,592
If the surface area of the box in the diagram is 204.25 square feet, what is the value of ‘x’?
the length is 10ft
the height is 6.5ft
what would x
A. 3 ft
B. 2.25 ft
C. 4.5 ft
D. 5 ft
Note: Consider x be the breadth of the box.
Given:
The surface area of the box is 204.25 square feet.
Length of the box = 10 ft
Breadth of the box = x ft
Height of the box = 6.5 ft
To find:
The value of x.
Solution:
The surface area of a cuboid is:
[tex]SA=2(lb+bh+hl)[/tex]
Where, l is length, b is breadth and h is height of the cuboid.
Putting [tex]SA=204.25, l=10,\ b=x,\ h=6.5[/tex] in the above formula, we get
[tex]204.25=2(10\times x+x\times 6.5+6.5\times 10)[/tex]
[tex]204.25=2(10x+6.5x+65)[/tex]
[tex]204.25=2(16.5x+65)[/tex]
Using distributive property, we get
[tex]204.25=2(16.5x)+2(65)[/tex]
[tex]204.25=33x+130[/tex]
[tex]204.25-130=33x[/tex]
[tex]74.25=33x[/tex]
Divide both sides by 33.
[tex]\dfrac{74.25}{33}=x[/tex]
[tex]2.25=x[/tex]
Therefore, the correct option is B.
Answer:
5.
The sum of three consecutive odd numbers is equal to thirteen more than two
times the largest number. Let the first odd number be'n'.
(a)
Write the equation of the problem
Answer:
(1 mark)
(b)
Solve for'n' to find the first number
Answer:
(1 mark)
(C)
What are the values of the second and third odd numbers?
Answer:
(1 mark)
(d)
Show that the equation is true.
Answer:
Let the numbers be n, n+2, n+4
Sum equals too= 13+2(n+4), which is 2n+21
a) Equation--> n+n+2+n+4= 2n+21
b) Solution--> 3n+6= 2n+21
=> n= 15
c) Second number--> 17 (15+2)
Third number--> 19 (15+4)
d) 15+15+2+15+4=30+21
=> 51= 51
So, the equation is true.
And pls mark me brainliesttt :)))
M∠1 is less than m∠2 by 40 degrees. What is m∠1 and m∠2
Find sets A and B such that A ∩ B = {3, 5} and A ∪ B = {2, 3, 5, 7, 8}
Answer:yes
Step-by-step explanation:99
find the number of terms in an AP given that it's first and last terms are a & 37a respectively and it's common difference is 4a
Answer:
Substitute the values give into the nth term of the arithmetic progression and solve this the steps are give above in the picture
Raquel needs to rent a car while on vacation. The rental company charges $19.95, plus 19 cents for each mile driven. If Raquel only has $40 to spend on the car rental, what is the maximum number of miles she can drive?
__________ miles
Answer:
105
Step-by-step explanation:
$40 - $19.95 = $20.05
$20.05 divided by 0.19 (19¢) = 105.526316
Answer:
105 miles
Step-by-step explanation:
40-19.95= 20.05
20.05/.19= 105.5263157895
round down to 105 miles
i need y’all help asap
IF YOU KNKW ABOUT THIS PLEASE HELP .... What is the volume of the cone shown below?
36
10
A. 3007 units
B. 12367 units3
C. 9007 units3
D. 1200 units 3
Answer:
A. 300π units³
Step-by-step explanation:
Formula for volume of a cone = ⅓πr²h
Where,
radius (r) = ½(10) = 5 units
height (h) = 36 units
Plug in the values and find the volume in terms of π
Volume of the cone = ⅓*π*5²*36
Volume of the cone = 300π units³
hey. I suck at algebra help pls?
Answer: 8
Hope this helps
In year 13, the scientist will put tree wrap around tree 1 to protect it from the winter snow. The height of the tree wrap needs to be 45 inches.
Answer:
22 feet²
Step-by-step explanation:
We are given:
height of tree h = 45 inches
Circumference= πd × inches
But d = 22.2inches
Therefore area will be
Area = 22.2π × 45 inches²
Area = 3137 inches²
Let's convert from inches² to feet², we have:
1 foot = 12 inches.
Therefore,
1 square foot = 1foot × 1foot = 12inches×12inches
= 3137inches² / 144 inches²
= 22feet²
Note: I attached missing data which states that diameter at year 13 is 22.2inches
Answer: 22
Step-by-step explanation:
simple
Express the ratio below in its simplest form. 1.5 : 1
Answer:
3 :2.
Step-by-step explanation:
1.5 : 1
Multiply both numbers by 2:
i this gives 3:2
Need to pass please help
please help me find the area
Answer:
165 square ft
Step-by-step explanation:
a bag contains 15 new batteries and 10 use batteries if Heather randomly so what's two batteries from the bag without replacement what is the probability that she will select a used battery and then a new battery
Answer:
1/4
Step-by-step explanation:
Probability is the number of desirable outcomes divided by the number of total outcomes. We can tell these events depend on each other because the batteries are picked without replacement. To find the probability of two dependent events, event that depend on each other, we can find the probability of the first event and the probability of the second event happens if the first is given and multiply them. In this case, the first event is selecting a used battery and the second is picking a new battery.
The total number of outcomes the basically the total amount of batteries that can be chosen. This is 15 + 10 or 25 outcomes. 10 of these batteries are used, and that would correspond to the amount of desirable outcomes because we want to pick a used one. From this, we can say the probability of picking a used battery is 10/25 which simplifies to 2/5.
To find the probability of picking a new battery after picking a used one, we can start by stating the amounts of each battery before the second draw. Since we already picked a used battery, our new totals will be 24 batteries, which 9 are used and 15 are new. Now, we can do the same thing a before, the number of desirable outcomes over the total. We get 15/24 which simplifies to 5/8.
To find the total probability, we multiply the two getting: 2/5 * 5/8 = 1/4.
HELP PLEASE PLEASEEEEEE
Answer: Well this one is simple too.
ATQ Angle 4 is 73° so the vertically opposite angle that is angle to will be the same, 73°.
now for the rest two.
lets find angle 1 first. If we find any one from this we can automatically get the other as they are vertically opposite angles.
Angle 1= 180 - Angle 4
Angle 1 = 180-73=107°
We found this coz the Angle 1 and 4 are on the same line which will form a straight angle.
hence, Angle 4 and 2 = 73°
Angle 1 and 3= 107°
Hope it helps. Pls mark brainliest
Find the largest possible rectangular area you can enclose, assuming you have 128 meters of fencing. What is the (geometric) significance of the dimensions of this largest possible enclosure?
Answer:
Step-by-step explanation:
let the length=x
width=y
P=2(x+y)=128
x+y=128/2=64
y=64-x
area A=xy=x(64-x)=64x-x²
[tex]\frac{dA}{dx} =64-2x\\\\\frac{dA}{dx} =0,gives~64-2x=0,x=32\\\frac{d^2A}{dx^2} =-2<0 ,at ~x=32[/tex]
so A or area is maximum if x=32
y=64-32=32
or it is a square of edge=32 meters.
Mrs. Bollo's second grade class of thirty students conducted a pet ownership survey. Results of the survey indicate that 8 students own a cat, 15 students own a dog, and 5 students own both a cat and a dog. How many of the students surveyed own only a cat?
a) 18
b) 15
c) None of these answers
d) 8
Answer:
c) None of these answers
Step-by-step explanation:
8 students own a cat
In this, we count the students who own both a dog and a cat, and the students who own only a cat.
5 students own both a cat and a dog.
So of the 8 who own a cat, 5 own both a cat and a dog, and 8 - 5 = 3 own only a cat.
So the correct answer is given by option c, as 3 is not an option.
A researcher conducted a paired sample t-test to determine if advertisements were viewed more in the morning (before noon) or in the evening (after 5pm) for eight different universities. The results were as follows:
Morning Evening
Morning Evening
Mean 32 40.625
Variance 89.71428571 504.5536
Observations 8 8
Pearson Correlation 0.343785438
Hypothesized Mean Difference 0
df 7
t Stat -1.152587077
P(T<=t) one-tail 0.143458126
t Critical one-tail 1.894578605
P(T<=t) two-tail 0.286916252
t Critical two-tail 2.364624252
Is there a significant difference between morning and evening access to the university advertisements?
a. Yes, there was a significant difference between Morning (M= 32), and Evening (M=40.625), (t [7] = .28, p < .05).
b. No, there was no difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15, p > .05).
c. Yes, there was a significant difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15 p < .05).
d. No, there was no difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15, p < .05).
Answer:
b. No, there was no difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15, p > .05).
Step-by-step explanation:
The critical value for one tailed test is t ∝(7) > 1.895
A one tailed test is performed to test the claim that advertisements were viewed more in the morning (before noon) or in the evening (after 5pm)
The null and alternative hypotheses are
H0: μm = μe vs Ha μm > μe
where μm is the mean of the morning and μe is the mean of evening.
The calculated value of t = -1.152587077 which is less than the critical region hence the null hypothesis cannot be rejected .
P(T<=t) one-tail 0.143458126 > 0.05
If two tailed test is performed the critical region is t Critical two-tail 2.364624252
and the calculated t value is -1.152587077 which again does not lie in the critical region .
Hence μm = μe or μm ≤ μe
P(T<=t) two-tail 0.286916252 > 0.025
Therefore
b. No, there was no difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15, p > .05).
Option b gives the best answer.
There are 12 marbles in a bag. 3
are green, 4 are blue, 3 are
yellow and 2 are red. One marble
is picked at random. What is the
probability that this marble is
blue?
Answer:
1/3 is the probability for the blue marbal
The width of the rectangle shown below is 10 inches the length is 4 feet what is the area of the rectangle in square inches
If the pool is to be 24 ft on each side, what is the length of one side of the hot tub?
Answer:
the side length of the hot tub = 4.8ft
Step-by-step explanation:
Scale Factor = 5
Also,
B'C' = 24 feet
Since both are squares so both have all sides equal.
Square A'B'C'D' is dilated by a scale factor of 5
So,
AB = BC = CD = DA = 24/5 = 4.8 ft.
i hope this helps you
The length of the one side of the hot tub is 4.8 ft.
What is Scale Factor?
The scale factor is a measure for similar figures, who look the same but have different scales or measures. Suppose, two circle looks similar but they could have varying radii. The scale factor states the scale by which a figure is bigger or smaller than the original figure.
Here, Richardo wants to build a square pool of the hot tub using a scale factor of 5.
If the each side of the pool is 24 ft.
The length of one side of hot tub = 24/5 = 4.8 ft.
Thus, the length of the one side of the hot tub is 4.8 ft.
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How many and what type of solutions does 7x^2−4x+3 have? 1 rational solution 2 rational solutions 2 irrational solutions 2 nonreal solutions
Answer:
2 non real solutions.
Step-by-step explanation:
We need to use discriminant,
for ax²+bx+c=0
The discriminat is b²-4ac
If the discriminant is,
→ less than 0, then 0 real solutions
→ equal to 0, then 1 real solutions
→ more than 0, then 2 real solutions
Given that,
7x²−4x+3=0
a=7, b=-4, and c=3
→ (-4)²-4(7)(3)
→ 16-84
→ -68
You can see this is less than 0, then non real solutions. [2 nonreal solutions]
Answer:
Solution given:
7x²-4x+3=0
taking common 7
7(x²+4/7*x+3/7)=0
x²+2*x*2/7+(2/7)²-(2/7)²+3/7=0
(x+2/7)²=-17/49
x+2/7=[tex]\sqrt{\frac{17}{49}}[/tex]
x=±√(17)/7-2/7
taking positive
x=√(17)/7-2/7
x=0.39
taking positive
x=-√(17)/7-2/7
x=-0.87
2:unreal number
