Anita's sister had $6000 to invest. She invested part of this sum at 4% and the other part at 6%. If the annual return on the 6% investment is $15 more than the annual return on the 4% investment, find how much is invested at 6% rate.

2550

Step-by-step explanation:

I'm assuming the interest is annual.

so this is breaking the 6000 into two parts, I am going to call them A and B.  i will say A is invsted at 4% and B is invested at 6%

It then tells us the amount of interest gaied from B is $15 more than the interest gained from A.  We basically use a system of equations.

A + B = 6000

.06B - .04A = 15

Let me know if you don't see how I got these equations.  I will go ahead and solve.

A + B = 6000

Gonna solve for A so I can plug it into the other eqaution and solve for B, which is what the question is asking for.  You can get both either way though.

A = 6000 - B

Plug this into the other equation.

.06B - .04A = 15

.06B - .04(6000 - B) = 15

.06B - 240 + .04B = 15

.1B = 255

B = 2550

this means A is 3450.  You can check by seeing what theinterest is for each.  

2550*.06 = 153

3450*.04 = 138

153 is 15 more than 138 so everything checks out.