In planning her​ retirement, Liza deposits some money at ​1.5% ​interest, with twice as much deposited at ​5%. Find the amount deposited at each rate if the total annual interest income is ​$1380.

Question

In planning her​ retirement, Liza deposits some money at ​1.5% ​interest, with twice as much deposited at ​5%. Find the amount deposited at each rate if the total annual interest income is ​$1380.

Answer 1

.015x+ .05(2x) = 1380

.115x = 1380

x = 1380/.115 = $12,000 invested at 1.5%

2x = $2400 invested at 5%

.015(12)+ .05(24)

=.18+1.2

=1.38K = 1380 total interest

total invested = $36000

1380/36000 = 138/3600 = 3.8333...% interest rate

5-3.8333...= 1.1666

3.8333-1.5 = 2.333

2.333/1.1666= 2 = 24000/12000