Question

Assume a quantity decreases by 6.7% in 8.6 hours.
What is the half-life of the substance? (answer should be accurate to two decimal places.)

Answer 1

let the equation be
amount = 1(1/2)^(t/k) , where k is the half-life, and t is number of hours

so (1 - .067) = 1(1/2)^(8.6/k)
logging it ...
log .933 = log (1/2)^(8.6/k)
8.6/k = log .933 / log .5
solve for k, your answer to half-life