Originally Posted by
red rose93
Charlie wants to buy a $300 stereo set in 8 weeks. How much should he invest now at 3% simple interest to have the money in 8 weeks?
Investment = $
My solution
simple interest
I=p*r*t
8 weeks= 8/52 year
I=300*0.03*8/52
=1.3846
You are being asked for the value of P, not the value of I. But the thing is, you don't have I either.
What you need to find is a sum, P, which when added to an interest I will give $300.
And you know r and t:
I = P * r * t
I = P(0.03)(8/52)
So:
P + I = $300
I = P(0.03)(8/52)
This is a simultaneous equation problem now. Can you solve it?