Question

Why do clothe merchant use metre scale

Answer 1

because cloth is measured by metre scale

Answer 2

Answer:

Answer : 20%

Assume the merchant purchases 1 metre (100 cm) cloth at Rs.100. 

Since he users 120 cm scale, he actually gets 120 cm of cloth. 
=> Cost price of 120 cm cloth = Rs.100
=> Cost price of 100 cm cloth = 100×100120=100012100×100120=100012

Assume the merchant sells 100 cm cloth. 
=> Selling price of 100 cm cloth = Rs.80 (∵ discount of 20%)

Since he uses 80 cm scale, he actually sells only 80 cm cloth and the cost mentioned above is the selling cost of 80 cm cloth.
i.e., Selling price of 80 cm cloth = Rs.80
=> Selling price of 100 cm cloth = 80×10080=10080×10080=100

Profit = (100−100012)×100100012(100−100012)×100100012

=(20012)×100100012=200×1001000=20%

I Hope It Will Help!
^_^