An automobile license plate consists of 4 letters followed by 3 digits. How many different plates can be made if repetitions are allowed in the letters and the digits must be odd (although repeats in the digits are allowed)? ​

Which account has the highest effective annual interest rate? not necessary but show how you got your answer.a. account 1: interest is compounded quarterly at an annual rate of 4.20%.b. account 2: interest is compounded monthly at an annual rate of 4.15%.c. account 3: interest is compounded semiannually at an annual rate of 4.10%d. account 4: interest is compounded annually at a rate of 4.25%.