Question

A college student Earned $6500 during summer vacation working as a waiter. The student invested Part of the money at 10% and the rest at 9%. If the student received a total of $607 in interest at the end of the year, how much was invested at 10%?

Answer 1

The amount invested at 10% rate is $ 2200

Explanation:

Given as :

The total amount earn by student = $6500

The total interest received at the end of year = $607

Let the amount invested at 10% rate = $x

So, The amount invested at 9% rate = ($6500 - $x)

Let the time for which money invested = 1 year

Now from Simple Interest method :

SI =
`(principal* Rate* Time)/(100)`

Or, SI_1 + SI_2 =
`(x* 10* 1)/(100)` +
`((6500-x)l* 9* 1)/(100)`

Or, SI_1 + SI_2 =
`((10x)/(100))+((6500-x)* 9)/(100)`

Or, $607 × 100 = 10x + (6500-x) × 9

Or, $60700 = 10x- 9x + 58500

Or, $60700 - $58500 = x

Or , 2200 = x

∴ x = 2200

So, The amount invested at 10% rate = $x = $ 2200

Hence The amount invested at 10% rate is $ 2200 Answer