Expert: Bobby Soltani - 2/24/2005

Question
Marvin had $900 to invest last year. He put some $$$   in a guaranteed 10% interest account. He put the remainder in a riskier acct. and lost 6% of the investment. If by the end of the year he lost $6 as a result of both investments, how much did he invest in each acct.?
How do I set up the equation? I'm getting lost at the "losing %6 and $6" and feel like I don't have enough info. Thanks
Briana

Answer
Hi Briana,

I'll help you set up the equations.  Let the amount invested in the guaranteed account be x and the remainder by y.  We know that x + y = 900.  So, that is our first equation.  Next, we know that the amount earned in the first account minus the amount lost in the second account is equal to -$6.00.  The amount earned in the first account is x*(0.10).  The amount lost in the second account is y*(0.06).  We can write this as:

x*(0.10) - y*(0.06) = -6

Now, we have two equations and two unknowns and we can solve the problem.  Substitute x = 900 - y in for x in the second equation and solve for y.  Then, use  x = 900 - y to solve for x.

Let me know if you have any questions.

Bobby