Question

A sum of money at simple interest amounts to rs. 815 in 3 years and to rs. 854 in 4 years. The sum is:

Answer 1

Answer:

Rs 698

Step-by-step explanation:

Let sum =100x and interest rate=Rs r/yr

Then sum after 3years

=100x+100x*r*3/100

=100x+3rx=815----------------(1)

Then sum after 4 years

=100x+100x*r*4/100

=100x+4rx=854----------------(2)

subtract (1) from(2)

rx=854-815=39

rx=39

from(1)

100x+3*39=815

100x=815-117

100x=698

so the sum=Rs 698

Answer 2

Answer:

• The required sum = Rs 698

Given:

• A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years.

Need to find:

• The required sum = ?

Solution:

• Simple Interest = Amount in 4 year's - Amount in 3 year's

Putting the values:

➪ Simple Interest of 1 year = 854 - 815

➪ Simple Interest of 1 year = Rs 39

Now,

• Simple interest of 3 years = Simple interest of 1 year - Given time

Putting the values:

➦ Simple Interest of 3 years = 39 × 3

➦ Simple Interest of 3 years = Rs 117

Again,

• Required sum = Amount in 3 years - Simple Interest of 3 years

Putting the values:

➜ The required sum = 815 - 117

➜ The required sum = Rs 698

Therefore:

• The required sum is Rs 698.

━━━━━━━━━━━━━━━━━━━━━━━━━━