The last of the GRE practice questions I had trouble with involve interest and functions from introductory Algebra.
- Pat invested a total of 3,000 dollars. 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?
We are expected to be able to solve this in about 1 minute or less. I tried plugging in the interest formulas and still couldn't solve it, even after 20m. Is there some simple formula I'm missing or heuristic I can follow that makes this doable in the allotted time?
- I'm also having trouble finding the x-intercepts for these two functions:
(a) f(x) = sqrt(x + 2)
(b) f(x) = x + |x|
That's all! Thanks.