Problem Solving

AAPL wrote: ↑

Mon Nov 22, 2021 2:54 pm

Magoosh

Jackson invested $300,000, dividing it all unequally between Account P and Account Q. At the end of the year, it turned out that Account P had earned 12% interest and Account Q had earned 25% interest. If Jackson earned a total of $60,000 in interest between the two accounts, which of the following is approximately the amount he put in Account P?

A. $115,384
B. $120,000
C. $121,072
D. $124,129
E. $130,000

OA A

We can solve the question using 1 variable or 2 variables. Let's use 1.

Let x = the money (in dollars) placed in Account P
So, $300,000 - x = the money placed in Account Q

Account P earned 12% interest and Account Q earned 25% interest, and Jackson earned a total of $60,000 in interest between the two accounts
We can write: (12% of x) + (25% of 300,000 - x) = 60,000
In other words: 0.12x + 0.25(300,000 - x) = 60,000
Expand: 0.12x + 75,000 - 0.25x = 60,000
Simplify: -0.13x + 75,000 = 60,000
Subtract 75,000 from both sides: -0.13x = -15000
Solve: x = 15,000/0.13 ≈ 115,000

Answer: A