SOLUTION: A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of interest from both investments is $91. How much is invested at 8%.

Question 76851: A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of interest from both investments is $91. How much is invested at 8%.
Answer by funmath(2933) (Show Source): You can put this solution on YOUR website!
A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of interest from both investments is $91. How much is invested at 8%.
Let the amount invested at 10% be: x
Then the amount invested at 8% is: 2x
The formula for simple interest is: I=interest, P=amount invested(known also as Principal) r=interest rate and t=time in years
Since they didn't give you time, I assume it is one year and can be ignored.
rate=8/100=.08 for 8%
rate=10/100=.10 for 10%
I=91
Problem to solve:

The amount invested at 10% is: x=$350
The amount invested at 8% is 2x=2($350)=$700 <--that's what they asked for.
Happy Calculating!!!!
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