3. (6pts) Calculate. a. If a savings account pays 7% interest, then according to the rule of 70 how long will it take for the account balance to double? b. For the above to triple? C. If a savings account pays 6.25% interest, then according to the rule of 70 how long will it take for the account balance to double? d. For the above to quadruple? 4. (Opts) Moxie Fox deposited $25,000 in a savings account at 7% interest compounded semiannually. At the beginning of year 4. Moxie deposits an additional $40,000 at 7% interest compounded semiannually. At the end of six years, what is the balance in Moxie's account