Shankara buys a watch for Rs. 1,950 in cash and sells it

Shankara buys a watch for Rs. 1,950 in cash and sells it for Rs. 2,200 at a credit of 1 year. If the rate of interest is 10% per annum, he _____ :

As per given question,
Amount A = 2200
Rate of Interest R = 10 %
Time = 1 year
S.P. = P.W. of Rs. 2200 due 1 year hence

Principle Amount = Rs.	A x 100
	100 + ( R x T )

Principle Amount = Rs.	2200 x 100
	100 + ( 10 x 1 )

Principle Amount = Rs.	2200 x 100
	110

Principle Amount = Rs. 20 x 100 = Rs. 2000
∴ Gain = Rs. (2000 − 1950) = Rs. 50.