A(t)=3900(1/2)^(t/14)

Question

The radioactive substance uranium-240 has a half-life of 14

 hours. The amount At of a sample of uranium-240 remaining (in grams) after t hours is given by the following exponential function. Find the amount of the sample remaining after 7  hours and after 50 hours. Round your answers to the nearest gram as necessary.

Answer 1

amount remaining after t hours =

3900(1/2)^(t/14)

how much left after 7 hours??

= 3900(1/2)^1/2 = 3900(1/sqr2) = 3900/sqr2 = about 3900/1.414 = about 2758

after 50 hours = 3900(1/2)^(50/14) = about 328

use a calculator