Question

Suppose an unknown radioactive substance produces 12800 counts per minute on a Geiger counter at a certain time, and only 800 counts per minute 10 days later. Assuming that the amount of radioactive substance is proportional to the number of counts per minute, determine the half-life of the radioactive substance.

Answer 1

Answer:

2.5 days.

Step-by-step explanation:

The number of half lives  is n where

12800(0.5)^n = 800

12800(0.5)^4 = 800

so n = 4

So the half life is 10/4

= 2.5 days.