Mixture problem help solve?

Question

Sally has $160,000 invested in an account that pays 5.5% interest. How much would she need to invest in an account that pays 6.7% interest to raise her combined yield to 6.2%?

Answer 1

You've submitted several similar problems; I'll do one & hope that what I provide can be helpful to you in solving others.  Interest on the 160K is 0.055(160,000) = $8,800 = I₁.

 

I guess she has OTHER MONEY (amt. x) available to invest at 6.7% (assuming 1 yr); this interest I₂ is 0.067x.

 

Her combined money is supposed to earn I₁ + I₂:

(160,000 + x) (0.062) = 8800 + 0.067(x).

 

You can solve this for x, the amount of additional money to invest at 6.7% in order to increase her combined yield to 6.2%.

 

This method is based upon my reading of the problem, which does not say take some of the 160K out and invest it in another account.