A shopkeeper bought locks at a rate of 8 locks for Rs 34 and sold them at a rate of 12 locks for Rs 57. Calculate:

1. his gain percent and

2. the number of locks he should sell to earn a profit of Rs 45. (PLZ answer soon exam approaching)

CP of 8 locks = 34

∴CP of 1 lock = = 4.25

SP of 12 locks = 57

∴SP of 1 lock = = 4.75

Thus, gain % is given by

where

Gain per lock = SP - CP = 4.75 - 4.25 = 0.50

Total profit to be earned = 45

∴ Number of locks to be sold = = 90

Thus, the shopkeeper needs to sell 90 locks to earn a profit of Rs 45.

**
**