Carbon-14 is a radioactive element with a half-life of about 5,730 years. Carbon-14 is said to decay exponentially. The decay rate is 0.000121. We start with one gram of carbon-14. We are interested in the time (years) it takes to decay carbon-14.

Seventypercent (70%) of carbon-14 will decay within how many years?

(b) Find the valueksuch thatP(x<k) =0.7.

(Round your answer to two decimal places.)

k=