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 .

Step-by-step 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 $\frac{5x}{100}$ . And, amount of money invested in 8% is twice that of 5% i.e. $\frac{(2)5x}{100} = \frac{10x}{100}$ .

Now, total investment is $720 so,

$\frac{5x}{100}$ +( $\frac{(2)5x}{100} = \frac{10x}{100}$ ) = $720

⇒ $\frac{5x}{100} + \frac{10x}{100} = 720$

⇒ $\frac{15x}{100} = 720$

⇒ $\frac{100(720)}{15} = x$

⇒ $x = 4800$

The amount invested by Mr.Smith in 5% is $\frac{5x}{100}$ i.e.$\frac{5(4800)}{100} = 240$. ∴ The amount invested by Mr.Smith in 5% is $240 .