# SOLUTION: You invest some money at 8% and half as much at 5%, you earn \$3150 in annual interest, how much did you invest at each rate?

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 Question 86955: You invest some money at 8% and half as much at 5%, you earn \$3150 in annual interest, how much did you invest at each rate?Answer by ptaylor(2052)   (Show Source): You can put this solution on YOUR website!Interest(I) equals Principal(P) times Rate(R) times Time(T) (Note: In this problem T=1 year) Let P=amount invested at 8% Interest at 8%=(P)(0.08)(1)=0.08P Then P/2=amount invested at 5% Interest at 5%=(P/2)(0.05)(1)=0.025P Now we are told that the interest accrued at 8% plus the interest accrued at 5% equals \$3150. So, our equation to solve is: 0.08P+0.025P=3150 collect like terms 0.105P=3150 divide both sides by 0.105 P=\$30,000------------------------------amount invested at 8% P/2=(30,000/2)=\$15,000---------------------amount invested at 5% CK 0.08*30,000+0.05*15,000=3150 2400+750=3150 3150=3150 Hope this helps----ptaylor