Question

Someone mind checking my work?

The radioactive substance cesium-137 has a half-life of 30 years. The amount A(t) (in grams) of a sample of cesium-137 remaining after t years is given by the following exponential function.

A(t)=381(1/2)^t/30

Find the initial amount in the sample and the amount remaining after 50 years. Round your answers to the nearest gram as necessary.

initial amount = 381
after 50 years = 1270

Answer 1

What do you mean?
I see no work.
A radioactive substance would have less grams after 50 years.
In other words, radioactive substances decreases in grams every year.

Answer 2

I sent my work down below where it says initial amount = 381
after 50 years = 1270

Answer 3

I plugged the information into my online calculator and that's what I got after 50 years.

Answer 4

You could at least say you plugged it in.
There was no indicator to what you did except put in the answer.

Answer 5

Because I dont think you plugged it right.

Answer 6

A(50)=381(1/2)^50/30 got me 1270

Answer 7

\[381 \times (0.5)^{\frac{ 50 }{ 30 }}\]

Answer 8

But my thing says to use the formula A(t)=381(1/2)^t/30

Answer 9

Same thing....
(1/2)=0.5

Answer 10

120.00748

Answer 11

That's what I got.

Answer 12

so rounding it would make it 120?

Answer 13

Yea me too.

Answer 14

Alright thank you

Answer 15

No problem!

Answer 16

@teller
Remember PEMDAS:
A(t)=381(1/2)^t/30 equals A(t)=381[(1/2)^t]/30 which is not correct.
You need to write
A(t)=381(1/2)^(t/30)
or else calculators will give wrong numbers. Calculators go strictly with PEMDAS, doesn't know what you want! xD

Answer 17

Yes exactly.
I tried figuring out what @teller did wrong, but couldnt figure on how to get 1270.