Question

Let us write by calculating the amount on Rs 80000 for 2½ years at the rate of 5% compound interest per annum.​

Answer 1

EXPLANATION.

Principal = ₹ 80,000.

Rate per annum = 5%.

Time = 2(1/2) years = 5/2 years = 2 years 6 months.

S.I = P x R x T/100.

Simple interest for first year = 80,000 x 5 x 1/100

Simple interest for first year = 4,000.

Amount in first year = 80,000 + 4000 = 84,000.

Simple interest for second year = 84,000 x 5 x 1/100

Simple interest for second year = 4,200.

Amount in second year = 84,000 + 4,200 = 88,200.

Simple interest for six months = 88,200 x 5 x 1/100 x 2.

Simple interest for six months = 2,205.

Amount in six months = 88,200 + 2,205 = 90,405.

Amount = ₹ = 90,405.

Answer 2

Given :-

• Principal = 80000
• Rate = 5%
• Time = 2½ = 5/2 years

To find :-

Amount

Solution :-

We know that

SI = PRT/100

Interest for the first year = ₹ (80,000 × 5 × 1)/100

Interest = 800 × 5 ×1/1

=4,000

Now

Amount = SI + P

A = ₹ (80,000+4,000)

A = ₹84,000.

Similarly

Interest for the second year = ₹ (84,000 × 5 ×1)/100

= 840 × 5 × 1/100

=4,200

A = (84,000+4,200)

A = ₹ 88,200.

Interest for 3rd years = ₹(88,200 × 5 ×1)/100 × 2

=₹ 2205

A = 88,200+2,205)

A =₹90,405