Question

A college student earned $7200 during summer vacation working as a waiter in a restaurant on the boardwalk at the beach. The student invested part of the money at 10% and the rest at 9%. If the student received a total of $680 in interest at the end of the year, how much was invested at 10% The amount invested at 10% was

Answer 1

Answer: The amount invested at 10% was $3200.

Step-by-step explanation:

Since we have given that

Principal amount = $7200

Rate of interest are 10% and 9%.

Total interest = $680

Let the amount invested on 10% be 'x'.

Let the amount invested on 9% be '7200-x'.

According to question, we get that

$\dfrac{x\times 10}{100}+\dfrac{(7200-x)\times 9}{100}=680\\\\10x+64800-9x=680\times 100\\\\x+64800=68000\\\\x=68000-64800\\\\x=\ 3200$

Hence, the amount invested at 10% was $3200.