The count rate of a radioactive material is 800 count/min. If the half-life of the material is 4 days, what would the count rate be in 16 days later
A
200 count / min
B
100 count / min
C
50 count / min
D
25 count / min
Verified Correct Answer: C.
Physical Principles & Numerical Solution
116 days = 4 half - lives
Thus, after 4 half lives the fraction left of any radioactive materials is given by (1/2)4 = 1/16
∴ Count rate / amount left = 1/16 x 800/1
= 50 count / min
Source: Myschool Past Questions Archive (Record #12749)