SOLUTION: Mark invested $12,500, part at 5% and part at 7% simple interest for a period of 1 yr. How much was invested in each account if the interest earned in the 7% account was $440 great

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Question 905835: Mark invested $12,500, part at 5% and part at 7% simple interest for a period of 1 yr. How much was invested in each account if the interest earned in the 7% account was $440 greater than the interest earned in the 5% account?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
We know the total amount of money invested. $12500
x+y=12500,
We know that the difference in interest earned by the two accounts is $440
0.07*x-0.05*y=440
x=12500-y
We substitute for x
0.07*(12500-y)-0.05*y=440
We multiply out
875-0.07y-0.05*y=440
We combine like terms.
435=0.12*y
Isolate y
y=435/0.12
y=3625 at 5%
Calculate x
x=12500-3625
x=8875 at 7%
Interest earned at 7% is 621.25
Interest earned at 5% is 181.25
We check
0.07*8875-0.05*3625=440
621.25-181.25=440
440=440
Since this statement is TRUE and neither amount is negative then all is well