SOLUTION: Susan invests 3 times as much money at 11% as she does at 7%. If her total interest after 1 year is $1600, how much does she have invested at each rate?
___ at 7% and ___at 11%
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___ at 7% and ___at 11%
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Question 1123789: Susan invests 3 times as much money at 11% as she does at 7%. If her total interest after 1 year is $1600, how much does she have invested at each rate?
___ at 7% and ___at 11% Answer by ikleyn(52776) (Show Source):
Let x be the amount Susan invested at 7%.
Then the amount invested at 11% is 3x dollars.
Your equation is
0.07x + 0.11*(3x) = 1600.
0.07x + 0.33x = 1600
0.4x = 1600 ====> x = = 4000 dolars.
Answer. $4000 at 7% and $12000 at 11%.
Check. 0.07*4000 + 0.11*12000 = 1600 dollars. ! Correct !
