Problem: A man has part of 4500 invested at 4% and the rest at 6%. If his annual return on each investment is the same, the average rate of interest which he realizes on the 4500 is
Answer Choices:
A. 5%
B. 4.8%
C. 5.2%
D. 4.6%
E. none of these
Solution:
x1​=21​(61​+41​)∴x=4.8;
or
Let y be the amount invested at 4%. Then .04y=.06(4500−y) and y=2700. Therefore the total interest is
.04(2700)+.06(1800)=216, and (216/4500)â‹…100=4.8%.