The half-life of chromium-51 is 26 days.?

Question

If a pharmaceutical sodium chromate solution registers 2400 counts per second today what will the count read in 78 days?

a.) 300 cps
b.) 1600 cps
c.) 1200 cps
d.) 600 cps

Answer 1

a

Answer 2

78 days is 3 half-lifes. So the count should be 1/2^3 = 1/8 of the current count