Problema Solution

K has a total of $1000 to invest.She puts part of it in an account paying 4% interest per year and the rest in a bond paying 6.5% interest. If she has $50 in simple interest at the end of one year, how much was invested at each rate?

One aluminum alloy is 35% aluminum.Another aluminum is 55% aluminum. How much of each should be used to make 1000g of aluminum alloy that is 40% aluminum?

Answer provided by our tutors

 4% interest: x

 6.5% interest: y

So

x+y=1000

4%x + 6.5%y = 50

So

x=600

y=400

So

4% interest: $600

 6.5% interest: $400