Question

Mr. Smith invests a certain amount of money at 8% and twice as much at 5%. If his annual income from the two investments is $720, how much does he have invested at 5%? (in $)

Answer 1

The amount invested by Mr.Smith in 5% is $240 .

Explanation:

We have , Mr. Smith invests a certain amount of money at 8% and twice as much at 5%. If his annual income from the two investments is $720 . Let us suppose that Mr.Smith invest $x so :

Amount of money invested in 5% is
`(5x)/(100)` . And, amount of money invested in 8% is twice that of 5% i.e.
`((2)5x)/(100) = (10x)/(100)` .

Now, total investment is $720 so,

`(5x)/(100)` +(
`((2)5x)/(100) = (10x)/(100)` ) = $720

⇒
`(5x)/(100) + (10x)/(100) = 720`

⇒
`(15x)/(100) = 720`

⇒
`(100(720))/(15) = x`

⇒
`x = 4800`

The amount invested by Mr.Smith in 5% is
`(5x)/(100)` i.e.
`(5(4800))/(100) = 240`. ∴ The amount invested by Mr.Smith in 5% is $240 .