Problema Solution
You are going to invest $25, 000, part at 14% and part at 16%. What is the most that can be invested at 14% in order to make at least $3,600 interest per year?
Answer provided by our tutors
let
x = amount invested at 14%
Interest earned in one year on this investment is 0.14x dollars.
Amount invested at 16% is 25000-x
Interest earned in one year on this investment is 0.16(25000-x) = 4000-0.16x dollars.
we want to find x in order to make at least $3,600 interest per year that is
interest for the part at 14% + interest for the part 16% >= total interest $3600
0.14*x + 4000 - 0.16*x >=3600
-0.02*x >=-400 multiply both sides by (-1)
x <= $20,000
$20,000 is the most that can be invested at 14% in order to make at least $3,600 interest per year.