Q: $1,500 is invested in two different accounts paying 4% and 5% interest. If a total of $67 interest is earned after one year, then how much money was invested at 4%?

A: We know that 1500 was invested total. [ We're trying to solve for the amount put into the 4% account.
Let's say that F was put in the 4% account (F for Four percent)
so the remaining money, or 1500 - F, was put into the 5% account.
initial deposits
4%- F
5%- -1500 - F
now, let's work it with words
total interest earned = interest from 4% account + interest from 5% account
total interest = (amt.

invested)(% interest) + (amount invested)(% interest)
67 = F(4%) + (1500 - F)(5%
67 = F(0.04) + (1500 - F)(0.05)
67 = F(0.04) + (1500)(0.05) - (F)(0.05)
67 = 0.04F + 75 - 0.05F
67 - 75 = 0.04F - 0.05F
-8 = -0.01F
-8 / -0.01 = F
F = 800
So $800 was invested in the 4% account (which means that 1500 - 800 = $700 was invested in the 5% account).
Check:
800 * 0.04 = 32
700 * 0.05 = 35
32 + 35 = 67 (There's our $67 total interest) ; Therefore $800 was invested @ 4% interest. ]

Expert answered|bongche|Points 1369|

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