## teller one year ago 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

1. anonymous

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.

2. teller

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

3. teller

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

4. anonymous

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

5. anonymous

Because I dont think you plugged it right.

6. teller

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

7. anonymous

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

8. teller

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

9. anonymous

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

10. teller

120.00748

11. teller

That's what I got.

12. teller

so rounding it would make it 120?

13. anonymous

Yea me too.

14. teller

Alright thank you

15. anonymous

No problem!

16. mathmate

@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

17. anonymous

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