Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t=0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed, as counts per seconds, at t=6, seconds is close to :

Options

A. 150
B. 400
C. 360
D. 200

Answer

B

Explanation

`A = A_0 e^(-lamda t)`
` 100 = 25600 e^(-lamda_8) rArr (1)/(256) = e^(-lamda_8) rArr e^(-lamda) = (1/256)^(3/4) = 25600 ((1)/(4^4))^(3/4) = (25600)/(4^3) = 25600/64 = 400`