Question

Mrs Shahbaz deposited Rs.12,200 in a bank at simple interest on her son's 15th birthday.When her son is 20 years old he recieves Rs.19520 .What was the rate of interest​

Answer 1

Answer:

Mrs Shahbaz deposited Rs.12,200 in a bank at simple interest on her son's 15th birthday.When her son is 20 years old he receives Rs.19520. The rate of interest​ was 12%

Step-by-step explanation:

The money was deposited when the son was 15 years old.

When her son reached 20 years the money had stayed in the account for (20 - 15) years.

= 5 years

So, in 5 years, Rs 12200 accumulated to Rs 19520

Now, let the interest rate be r.

Simple interest = P × r × t

= 12200 × r/100 × 5

= 610 r

So the amount in the account is:

= 12200 + 610r = 19520

610r = 19520 - 12200

610r = 7320

r = 7320/610 = 12%

The rate of interest was 12%

Answer 2

The rate of interest was 12%.

Step-by-step explanation:

Mrs Shahbaz deposited ₹ 12,200 in a  bank at simple interest on her son's 15th birthday.

After 5 years when her son is 20 years old she received ₹ 19,520.

We will calculate the rate of interest by this formula :

$(\frac{1}{t} )(\frac{A}{P}-1 )$

Where A = Future amount (19,520)

           P = Principal amount (12,200)

           t = time (5 years)

Now put the values into the formula

= $(\frac{1}{5})(\frac{19520}{12200}-1 )$

= $(\frac{-1}{5})+ (\frac{8}{25})$

=  $\frac{3}{25}$ = 0.12

0.12× 100 = 12%

The rate of interest was 12%.

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