SOLUTION: Jack invests $1500 at a certain annual interest rate, and he invests another $3000 at an annual rate that is one-half percent higher. If he receives a total of $285 interest in 1 y

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Question 366078: Jack invests $1500 at a certain annual interest rate, and he invests another $3000 at an annual rate that is one-half percent higher. If he receives a total of $285 interest in 1 year, at what rate is the $1500 invested?
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Let r be the rate at which the $1500 is invested. Thus r + .005 is the rate at which the $3000 is invested at (be careful on the decimal point)...thus we have
1500r + 3000(r + .005) = 285
Multiply through and get
1500r + 3000r + 15 = 285
Collect and get
4500r + 15 = 285
Subtract 15 and get
4500r = 270
Now divide by 4500 and get
r = .06 = 6%