OG:pg 244, #13

[jacobsonkatheryn]

Pat invested a total of $3,000. Part of the money was invested in a money market account that paid 10 percent simple annual interest, and the remainder of the money was invested in a fund that paid 8 percent simple annual interest. If the interest earned at the end of the first year from these investments was $256, how much did Pat invest at 10 percent and how much at 8 percent?

I'm missing the middle piece.. $3,000 x 1.10 = $300 and $3,000 x 1.08 = $240... the total for 1 year is $256....

Katie

[tommywallach]

Hey Katheryn,

The problem is you're acting like all of the money was invested simultaneously at the two rates. That's not possible. SOME of it was invested at 10%, and some at 8%. You're going to need algebra.

x * .1 (10% of some amount)
(3000 - x) * .08 (8% of the remaining amount)

If we add these up, we should get 256:

.1x + 240 - .08x = 256
.02x = 16
x = 800

So 800 was invested at 10%, and the remaining 2200 at 8%.

-t