Chapter 7.7, Problem 26E

Radioactive material decays over time and the amount remaining at time

t is given by the equation

$amount remaining=initial amount\times \left(\frac{1}{2}\right)\frac{t}{h}$,

where h is the half-life of the material, which is the time it takes the

material to decay to one-half its original amount. Use this equation in

Exercises 25 and 26.

If we have 100 pounds of radioactive uranium-238, which has a

half-lie of about 4.7 billion years, how much will still remain after 1

billion years?