Question

If interest is compounded continuously, the following equation relates the amount of time t it takes for an investment to double in value to the annual interest rate r:
2P=Pert.
a. Solve the equation for t in terms of r.
b. How long does it take for an investment to double in value compounding continuously if the annual interest rate is 7%?
Round your answer to the nearest tenth of a year.
c. Solve the equation for r in terms of t.
d. What interest rate is necessary for an investment to double in value in 7 years if interest is compounded continuously?
Round your answer to the near

Answer 1

So far I have:
a) t= ln(2)/r + ln(P)/r
b) t = 14.3
c) r = ln(2)/t + ln(P)/t

Answer 2

Also it's suppose to be 2P=Pe^rt