DRDO Multi tasking staff Model paper 9

Tips & Tricks
Now, cost price of 100 g is Rs. 100
But instead of 100 g he sells 80 g at the price of 100 g
So, 80 g is sold at Rs. 100
Actual cost price of 80 g = Rs. 80
Actual selling price of 80 g = Rs. 100
Profit = [(selling price – cost price)/cost price] × 100
⇒ profit = [(100 - 80)/80]× 100 = (20/80) × 100 = 25%
Short Trick:
Profit% = [(true weight - false weight)/false weight] × 100
⇒ profit% = [(100-80)/80] × 100 = 25%