1. What annual rate of interest would you have to earn on an investment of $2500 to ensure receiving $182.50 interest after 1 year?
2. Phyllis invested $9,000, a portion earning a simple interest rate of 3/2% per year and the rest earning a rate of 2% per year. After one year the total interest earned on these investments was $215.00. How much money did she invest at each rate?
Thanks
1 - 182.50 /2,500 ==0.073 x 100 ==7.3% annual interest rate
2 - There is a mistake in this question! One of the interest rates is wrong! Check the numbers carefully.
Let the amount invested at 5/2% ==P
Then, the amount invested at 2% ==9,000 - P
5/2 ==2.5%
0.025P + 0.02 * [9,000 - P] ==215, solve for P
0.025P + 180 - 0.02P ==215
0.025P - 0.02P ==215 - 180
0.005P ==35
P ==35 / 0.005 ==$7,000 - invested at 5/2%
9,000 - 7,000 ==$2,000 - inested at 2%