Calculating Inflation rates

In a country where inflation is a concern, prices have risen by 40% over a 5-year period.

a) By what percent do the prices rise each year?

b) How long does it take for prices to rise by 5%?

So how would I start out this problem? When it says inflation that means the prices are going up.

Should I use this formula:

P0e^k*t = P0

e^k*5 = 1.4 to solve and find the answer to a?

If so then should the answer to a) be 0.067294447 or 6.7294447%?

Also for b) should the set up be like this?

1(1.067294447)^t = 1.05? Solve for t

If so should the answer to b) be 0.749155419?

Please help me with theses problems. Thank you.