a$.$ If the interest rate is $7\mathrm{.}4\%$ per year, approximately how long will it take for your money to quadruple in value?

Note: Use the Rule of $72.$ Round your answer to $2$ decimal places.

Number of years $,19\mathrm{.}46$

b$.$ If the inflation rate is $4\mathrm{.}7\%$ per year, what will be the change in the purchasing power of your money over this period? Note: Use the Rule of $72$ to compute the number of years. Do not round intermediate calculations. Enter your answer as percent rounded to $2$ decimal places.

Purchasing power

by

$\%$