Question

Linda invested some amount in bank A at 5% per annum and the same amount at 7% per annum in bank B. At the end of 4 years she received a total of $7440. How much money did she invest in bank A?
Note: The banks are offering simple interest on all the amounts.

• A. $3000
• B. $4000
• C. $6000
• D. $2000

Answer 1

The correct option is A $3000

Let the individual amount invested in bank A and bank B $=x$

We know:
Amount $=$ Principal (1 + Rate $\times$ Time)

Amount received from bank A after 4 years
$=x(1+\frac{5}{100}\times 4)$

$=x(1+\frac{20}{100})$

Amount received from bank B after 4 years
$=x(1+\frac{7}{100}\times 4)$

$=x(1+\frac{28}{100})$

Total amount received
$=x(1+\frac{20}{100})+x(1+\frac{28}{100})$

$=2x+\frac{(20+28)x}{100}$

$=2x+\frac{48x}{100}$

$=\frac{200x+48x}{100}$

$=\frac{248x}{100}$

Total amount received $=\$7440$

$\frac{248x}{100}=7440$

$x=\frac{7440\times 100}{248}$

$x=\$3000$

Hence, Linda invested $3000 in bank A.