Nirav and Mehul borrowed Rs.4000 and Rs.5000 respectively for 2.5 years at the rate of x% per annum. Mehul paid Rs 125 more interest than Nirav. Find x.

Formula Used:

SI = PRT ÷ 100

where SI is simple interest, P is the principle value, R is the rate of interest and T is the time for which interest is paid.

Calculation:

Rate = x %  and Time = 2.5  years

For Nirav,
P =  Rs. 4000 
⇒  \(SI=\frac{4000 \times 2.5 \times x}{100}=100 x \)
For Mehul,
P = Rs. 5000 
⇒ \(S I=\frac{5000 \times 2.5 \times x}{100}=125 x \)

Mehul paid Rs 125 more interest than Nirav

⇒ 100x + 125 = 125x 
⇒ 25x = 125 
⇒ x = 5

Hence, x is 5.