SOLUTION: An amount of money invested for 1 year in a savings account will earn $1,200. That same amount of money invested in a mini-mall development will earn $4,200 interest in a year, bec

Question 1034389: An amount of money invested for 1 year in a savings account will earn $1,200. That same amount of money invested in a mini-mall development will earn $4,200 interest in a year, because the interest paid is 10% more than that paid by the savings account. Find the rate of interest paid by each investment.
Answer by jorel555(1290) (Show Source): You can put this solution on YOUR website!
Our equation for interest is I=P(r) where I is the interest,P is the principal, and r is the rate of interest. Solving for P:
I=P(r)
P=I/r
So
1200/r=4200/r+10
1200r+12000=4200r
3000r=12000
r=4
r+10=14!!!!!!!!!
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