Question

A radio active substance has a half life of 20-days

how much time is required so that only 1/32 of the original amount remains?

Find the rate of decay at this time..

Answer 1

2^5 is 32, so it would take 5x20 days, or 100 days.

Answer 2

ok. what about the rate of decay?

Answer 3

Well every 20 hours it decreases by half.

Answer 4

so however many hours divided by 20 with a negative sign made as the exponent of 2 would give you the answer

Answer 5

for example, 200 hours. 200/20=10 2^-10=1 over 1024