interest rate

Question

The annual interest on an $11,000 investment exceeds the interest earned on a $2000 investment by $392. The $11,000 is invested at a 0.7% higher rate of interest than the $2000. What is the interest rate of each investment?

Answer 1

Let x = interest rate in decimal form on $2000 investment

then interest rate on $11,000 investment is x+0.007

then annual interest earned assuming simple interest is 

11000*(0.007+x) = 392 + 2000*(x) 

solve for x(11000-2000) = 392-11000*(0.007)

x = 0.035 = 3.5%