Applications of Exponential & Logarithmic Functions

Question

An unknown radioactive element decays into non-radioactive substances. In 880880 days the radioactivity of a sample decreases by 7777 percent.

(a) Find the decay constant kk. (Round your answer to 5 decimal places.)

k≈k≈  

(b) What is the half-life of the element? (Round your answer to two decimal places)

half-life:    (days)

(c) How long will it take for a sample of 100100 mg to decay to 7878 mg? (Round your answer to two decimal places)

time needed:    (days)

Answer 1

0.77 = e^880k

Can you solve for k?

0.5 = e^kt, use value of k from above and solve for t.