Friday

August 29, 2014

August 29, 2014

Posted by **trace** on Thursday, September 16, 2010 at 4:40pm.

amount is 183.9 grams.

(a) Fill in the right hand side of the following equation which expresses

the amount A of the substance as a function of time t (the coefficient of t in the exponent should have at least four significant digits):

(b) When will the substance be reduced to 2.4 grams?

(use decimals.)

- calculus -
**drwls**, Thursday, September 16, 2010 at 7:33pmThere is not "followiong equation" to fill in.

Amount left = 183.9*2^(-t/31)

You don't need 4 sig figs in the exponent in this form if the half life is exactly 31 days.

(b) When amount left = 2.4,

2.4/183.9 = 0.01088 = 2^(-t/31)

-4.5212 = (-t/31)*ln 2 = -0.02236t

t = 202.2 days

- calculus -
**annonymous**, Thursday, September 16, 2010 at 8:06pmthe second answer is 194.052 days

**Related Questions**

algebra - Andrew measures they amount of a very unstable substance to be 100 ...

Math/Calculus - After 5 days, a particular radioactive substance decays to 37% ...

calculus - The rate at which an amount of a radioactive substance decays is ...

Alegbra - Andrew measures the amount of a very unstable substance to be 100 ...

calculus - Assume a substance has a half-life of 11 years and the initial amount...

math - assume the substance has a half-life of 11 years and the initial amount ...

Math, science - assume the substance has a half-life of 12 years and the initial...

Calculus Help Please!!! - A radioactive substance has a half-life of 4 days. ...

Math - assume the substance has a half-life of 11 years and the initial amount ...

Chemistry Help Please!!! - A radioactive substance has a half-life of 4 days. ...