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ExtremeBDS [4]
3 years ago
11

A certain radioactive isotope is a​ by-product of some nuclear reactors. Due to an​ explosion, a nuclear reactor experiences a m

assive leak of this radioactive isotope.​ Fortunately, the isotope has a very short​ half-life of days. Estimate the percentage of the original amount of the isotope released by the explosion that remains days after the explosion.
Mathematics
1 answer:
hodyreva [135]3 years ago
8 0

Answer:

73.5%

Step-by-step explanation:

The question is incomplete, the complete question is shown in the image attached.

Half life (t1/2) = 9 days

Time taken (t) = 4 days

From;

0.693/t1/2 = 2.303/t log (No/N)

Substituting values;

0.693/9 = 2.303/4 log(No/N)

0.693/9 × 4/2.303= log(No/N)

2.772/20.727= log(No/N)

Antilog (2.772/20.727)=No/N

1.36 = No/N

Therefore;

N/No = (1.36)^-1

N/No = 0.735

Percentage remaining after 4 days= 0.735× 100= 73.5%

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The distance around the middle of a sphere (the circumference) equals 37.699 in. what is the surface area of the sphere?
podryga [215]

To solve this problem you must apply the proccedure shown below:

1. Clear the radius from the formula for the circumference of a circle and substitute values, as following:

C=2\pi r\\ r=C/2\pi \\ r=37.699in/2\pi \\ r=5.99in

2. Substitute the radius calculated into the formula for calculate the surface area of the sphere:

SA=4\pi r^{2} \\ SA=4\pi(5.99in^{2})\\ SA=450.88in^{2}

The answer is: 450.88in^{2}

5 0
3 years ago
Brielle and Joshua are running a half marathon race, which is 13.1 miles long. It takes Brielle 10 minutes to run 1.25 miles and
CaHeK987 [17]

Answer: Brielle will run the marathon faster.

Brielle = 104.8 minutes  

Joshua = 157.2 minutes

Step-by-step explanation:

Speed rate = distance /time

Brielle = 1.25 /10 = 0.125 miles per minute

Joshua = 1.5/18 = 0.083333 =1/12 miles per minute

Since 0.125 (Brielle) > 1/12 (Joshua)

Brielle will run the marathon faster.

To calculate the time that takes each one to run the entire race (13.1 miles)

Time= distance / speed

  • Brielle = 13.1 /0.125 = 104.8 minutes
  • Joshua = 13.1 / (1/12)= 157.2 minutes

Feel free to ask for more if needed or if you did not understand something.

8 0
3 years ago
We are currently learning triangle similarity and about dilations in geometry. We have been using cross multiplying to figure th
miss Akunina [59]
Took me a minute to think.

Form ratios.

x, the small triangle, forms a ratio with 6, the big triangle.

The part of the side that is equal(with the dash) that is part of the small triangle is equal to 6-x, the big triangle.

Yes, you can cross-multiply here!

\frac{6}{x}  =  \frac{8}{6-x}

<em>Now,</em><em> </em>cross multiply.
P.S. Use distributive property.

36-6x = 8x

Add 6x on both sides.

36=14x

Divide by 14 on both sides.

x = \frac{36}{14} = \frac{18}{7}



4 0
3 years ago
I don't really understand, please help!!
miv72 [106K]

Step-by-step explanation:

the proof is given above

4 0
3 years ago
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Answer:

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Step-by-step explanation:

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