Sriram G. answered 04/28/13
Your friendly neighborhood TUTOR (Maths & Physics)
Hello Miranda,
A=pe^kt
=> ln(A) = ln(pe^kt) 'ln' is natural logarithm, logarithm function to the base 'e' [loge]
= ln(p) + ln(e^kt) log (xy) = log(x) + log(y)
= ln(p) + kt loge(en) = n loge(e) ; loge(e) = 1
=> t = [ln(A) - ln(P)]/k
Now you are given values of P, A and k. Plug them in to get t.
Note: Look into the units of your problem. You are asked to find time in hours. The units of your answer depend on the units of 'k'. If k has different time units, convert your answer to hours.
Good Luck !