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My name is Ann [436]
3 years ago
7

A radioactive substance decays according to the formula

Mathematics
1 answer:
Leviafan [203]3 years ago
7 0

Answer:

t=4820 y

Step-by-step explanation:

a) The half-life equation is given by:

t_{1/2}=\frac{ln(2)}{k}

b) Using the decay equation we have:

Q(t)=15e^{-0.0001438t}

we need to find t when Q(t)=\frac{Q_{0}}{2}

7.5=15e^{-0.0001438t}

0.5=e^{-0.0001438t}

ln(0.5)=-0.0001438t

t=\frac{ln(0.5)}{-0.0001438}

t=4820 y

Therefore, it will take 4820 years to decay to half the original amount.

I hope it helps you!

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two circles are externally tangent to each other. One circle has a diameter of 62 yards and the distance between the centers of
maksim [4K]

Answer:

108 yards

Step-by-step explanation:

Let circle A be the circle with the 62 yard diameter

Let circle B be the circle whose diameter we are trying to solve for.

  • Externally tangent circles are circles which touch each other and share a common external tangent.
  • Circle A has a tangent of 62 yards and thus a radius ( half the diameter) of 31 yards.
  • The distance between the centers of the 2 circles is 85 yards. If you subtract the radius ( distance from the center of the circle to its circumference) of circle A then we'll only be left with the radius of circle B.
  • 85 - 31= 54 yards which is the radius of circle B
  • To get the diameter: 54 x 2 = 108 yards

8 0
3 years ago
An urn contains 2 red marbles and 3 blue marbles. 1. One person takes two marbles at random from the urn and does not replace th
Ghella [55]

Answer:

A) The best way to picture this problem is with a probability tree, with two steps.

The first branch, the person can choose red or blue, being 2 out of five (2/5) the chances of picking a red marble and 3 out of 5 of picking a blue one.

The probabilities of the second pick depends on the first pick, because it only can choose of what it is left in the urn.

If the first pick was red marble, the probabilities of picking a red marble are 1 out of 4 (what is left of red marble out of the total marble left int the urn) and 3 out of 4 for the blue marble.

If the first pick was the blue marble, there is 2/4 of chances of picking red and 2/4 of picking blue.

B) So a person can have a red marble and a blue marble in two ways:

1) Picking the red first and the blue last

2) Picking the blue first and the red last

C) P(R&B) = 3/5 = 60%

Step-by-step explanation:

C) P(R&B) = P(RB) + P(BR) = (2/5)*(3/4) + (3/5)*(2/4) = 3/10 + 3/10 = 3/5

3 0
3 years ago
How do i divide using polynomial long division
Umnica [9.8K]
1.divide the first term of the numerator by the first team of the denominator, and put that in the answer
2. Multiply the denominator by that answer, put that below the numerator
3.subtract to create a new polynomial
3 0
3 years ago
I need help with Which table shows the correct methods used to justify the solution steps?
12345 [234]

Answer:

x = 8

Step-by-step explanation:

3 (x - 5) + 7x = 65

3x - 15 + 7x = 65

10x - 15 = 65

10x = 80

x = 8

5 0
3 years ago
Read 2 more answers
in parallelogram JKLM, the ratio of the measure of angle J to the measure of angle M is 5:4. Find the measurement of angle J and
Helga [31]
Since we know that these two are consecutive angles and consecutive angles add up to 180 deg, we can come up with the equation 4x +5x =180. Solving this out shows us that x = 20 and the measure of angle J is 100 deg while the measure of angle M is 80 deg. 
5 0
3 years ago
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