A dealer professing to sell at cost price uses a 900 gms weight for a kilogram. His gain percent is:________?

A dealer professing to sell at cost price uses a 900 gms weight for a kilogram. His gain percent is:________?

A. 9
B. 10
C. 11
D. 11 1/9
Explanation:
Gain % = {Error/(True value – error) × 100} %
= (100/900 × 100)% = 11 1/9%