How much was invested in the 8% account?

Question

A total investment of $9,600is made into two savings accounts. One account yields 8% simple interest and the other 9% simple interest. He earns a total of $827.00interest for the year. How much was invested in the 8% account?

Answer 1

Let x = the amount invested in the 8% account.

And let y = the amount invested in the 9% account.

 

Since the total investment is 9600, that means that x + y = 9600.

 

Now we need another equation.  Let's look at the information we have about earnings.

 

The amount earned by the 8% account is .08x.

The amount earned by the 9% account is .09y.

 

So .08x + .09 y = 827.

 

So we have to solve the two equations:

 

x + y = 9600

.08x + .09 y = 827

 

Let's use substitution.  The first equation tells us that y = 9600 - x.  So plugging that into the second equation gives:

 

.08x + .09 (9600 - x) = 827      -- substitute 9600 - x for y

.08x + 864 - .09x = 827           -- simplify

-.01x + 864 = 827                   -- combine x terms

-.01x = -37                              -- subtract 864 from both sides

x = 3700                                 -- divide both sides by .01

 

Since the total has to be 9600, y = 5900