Question

Plzzz solve this I will mark u as the brainiest.

A sum of the money deposited in post office , amounts to Rs 1250 in 5 years and Rs 1400 in 8 years , find the sum and the interest carried every year , if the interest is calculated yearly.

Answer 1

The sum is Rs 3125 and the interest for a year is Rs 156.25

Let the principal money (P) be = Rs P.

Rate be R% p.a.

Time (T) be 5 years.

So, SI = PRT/100

= 5PR/100

= PR/20

Total amount = P + PR/20

This is equal to Rs 1250

So, P(1+R/20) = 1250

Again, When time is 8 years, Amount is Rs 1400.

So,

SI = 8PR/100

Amount = P + 2PR/25

So, P(1+2R/25) = 1400

(1 + 2R/25)/(1 + R/20) = 1400/1250

⇒ (25+2R/25)(20+R/20) = 28/25

⇒ 25 + 2R = 7(20+R)/5

⇒ 25 + 2R = 140/5 + 7R/5

⇒ 25 + 2R = 28 + 7R/5

⇒ 3R/5 = 3

⇒ R = 5% p.a

As 8P(5)/100 = 1250

⇒ P = Rs 3125

SI for 1 year = 3125*5*1/100 = Rs 156.25