. An investment of $4600 is made at an annual simple interest rate of 6.8%. How much additional money must be invested at an annual simple interest rate of 9% so that the total interest earned is 8% of the total investment?

the additional amount to be invested is $5520

Step-by-step explanation:

Let x represent the additional amount of money that should be added.

An investment of $4600 is made at an annual simple interest rate of 6.8%. It means that the amount of interest that would be made from this amount after 1 year is

6.8/100 × 4600 = $312.8

$x would be invested at 9%. It means that the amount of interest that would be made from this amount after 1 year is

9/100 × x = $0.09x

If the total interest to be earned is 8%, It means that the amount of interest that would be made from the total amount after 1 year is

0.08(x + 4600)

Therefore,

0.09x + 312.8 = 0.08(x + 4600)

0.09x + 312.8 = 0.08x + 368

0.09x - 0.08x = 368 - 312.8

0.01x = 55.2

x = 55.2/0.01

x = $5520