Sunday

January 25, 2015

January 25, 2015

Posted by **zak** on Thursday, February 26, 2009 at 11:21pm.

I know that I am suppose to use

y= ye^kt , to get the equation and then plug in the info. to get the time, but I'm not sure how to start, please help! Thanks!

- calculus -
**Reiny**, Thursday, February 26, 2009 at 11:55pmy = a e^(kt) where a is the initial amount

so y = 10(e^(kt))

when t = 24100, y = 5 ---> you should have 1/2 of the original 10 g left.

0.5 = e^(24100k)

24100k = ln(0.5)

k = ln(.5)/24100

so y = 10(e^(t)(ln.5/24100))

so you want y to be 1

1 = 10 (e^(t)(ln.5/24100))

0.1 = (e^(t)(ln.5/24100))

(t)(ln.5/24100)) = ln .1

t = 80059

so about 80,000 years !!!!

- calculus -
**zak**, Friday, February 27, 2009 at 3:06amOhhh, I get it!! Thanks so much, you helped me a lot! :)

**Answer this Question**

**Related Questions**

Math - _The_Natural_Base_e_ An accident in 1986 at the Chernobyl nuculear plant ...

science - suppose you have 100grams of radioactive plutonium-239 with a half-...

CHEM - Pu-239 has a half-life of 24110 y. If 1.00 kg of this isotope is present ...

CHEMISTRY - Suppose you had a detection device that could count every decay ...

Physics - Suppose you have 100 g of radioactive plutonium-239 with a half-life ...

Physics - Suppose you have 100 g of radioactive plutonium-239 with a half-life ...

Chemistry - Plutonium-239 is used in nuclear bombs. Determine the number of ...

Math Analysis - 31. Radioactive decay of material is determined using the ...

Chemistry - How much a 2.00 g 239 Pu would have decayed after 1.6 x 10^4 years? ...

AP Calculus - An Initial amount of 100 grams of Thorium-234 decays according to ...