Math word problems

Question

Walter and Barbara invested $5000 in two CD’s last year. One of the CDs paid 4% interest. The other one paid 5% interest. At the end of one year they earned $228 in simple interest. How much did they invest at each interest rate?

What do we need to find?

Amount invested at 4%: 

Amount invested at 5%:

___ % ( $ x ) + ___ % ( $_______ - x ) = interest

Write the equation:

Solve the Equation:

so if they invest 2400 in the 7% CD and 2600 in the 6% CD they will have 168 from the 7% and 156 from the 6% for a total interest of 324

Amount invested at 4% is $ __________________________

Amount invested at 5% is $ __________________________

Answer 1

.04X + .05(5,000-X)= 228

-0.01X = 228- 250

0.01X = 22

X = 22/0.01 = $2,200 invested at 4%

5,000-X = $2,800 invested at 5%

228/5,000 = 4.56%, which is a little closer to 5% than to 4%, so a little more is invested at 5% relative to 4%

4% of 2200 = $88, 5% of 2,800 = 140, 140+88= $228 total interest