How much of a radioactive substance must be presented to decay to 60 grams in 11 years if the half-life of the substance is 3.9 years?

Question

Select one:

a. Between 400 and 420 grams

b. Between 420 and 440 grams

c. Between 440 and 460 grams

d. Over 460 grams

Answer 1

x * (1/2)^(11/3.9) = 60
now just solve for x