Question

Sammy wants to deposit into a 7% annual simple interest account she will also deposit twice as much in a certificate of deposit earning 5% annual simple interest to earn $390 of annual interest how much should she invest in each account?​

Answer 1

Answer: $2294 should be invested in the simple interest account while $4588 should be invested in the certificate of deposit.

Explanation:

Let x represent the amount that he would deposit in the simple interest account.

Let y represent the amount that he would deposit in the certificate of deposit.

she will deposit twice as much in the certificate of deposit. It means that

y = 2x

Interest from the simple interest account would be 7%. This mean that the interest would be 7/100 × x = $0.07x

Interest from the certificate of deposit account would be 5%. This mean that the interest would be 5/100 × y = $0.05y.

The total interest from both accounts would be $390. It means that

0.07x + 0.05y = 390- - - - - - - - - - 1

Substituting y = 2x into equation 1, it becomes

0.07x + 0.05 × 2x = 390

0.07x + 0.1x = 390

0.17x = 390

x = 390/0.17 = $2294

y = 2x = 2 × 2294

y = 4588