SOLUTION: hello I am really struggling with this word problem: A high school student was able to save $3000 by working a part-time job every summer. He invested half the money in a money

Question 400831: hello I am really struggling with this word problem:
A high school student was able to save $3000 by working a part-time job every summer. He invested half the money in a money market account and half the money in a stock that paid three times as much interest as the money market account. After a year he earned $90 in interest. What were the interest rates of the money market account and the stock?
Answer in percentages and round to one decimal place.
Thank you.

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A high school student was able to save $3000 by working a part-time job every summer.
He invested half the money in a money market account and half the money in a stock that paid three times as much interest as the money market account.
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1500 invested at r
1500 invested at 3r
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After a year he earned $90 in interest.
What were the interest rates of the money market account and the stock?
Answer in percentages and round to one decimal place.
----
Equation:
interest + interest = interest
1500r + 1500(3r) = 90
1500r + 4500r = 90
6000r = 90
r = 0.015 or 1.5% (money market investment rate)
3r = 0.045 or 4.5% (stock investment rate)
============================
cheers,
stan H.
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