Question

1.If the cost price of 2 pencils is equal to the selling price of 5 pencil,then the loss % is what?(please explain in detail I am not so intelligent).

2.If the cost price of 4 toffees is equal to the selling price of 3 toffees then the gain % is what?

Answer 1

in these types of questions one can assume the initial price to be rs.10 or rs.100 or any such value.
i will explain both the general method and the assumption method

General Method:

1.
Let the price of each pencil be x
then for 2 pencils the price will be 2x

he sell 5 pencils at this price.
if he had sold it at the original price he should have received 5x, but now he only receives 2x  for 5 pencils.
so the loss % = (orignal CP - SP) / original CP
=> (5x-2x)/5x
= 60%

2.
Let the price of each toffee be x
then for 4 pencils the price will be 4x

he sell 3 toffees at this price.
if he had sold it at the original price he should have received 3x, but now he receives 4x  for 3 pencils.
so the gain % = (SP - orignal CP) / original CP
=> (4x-3x)/3x
= 33.33%

Assumption Method:

1.
let one pencil cost rs.10
two pencils cost rs.20
he sells 5 pencils for 20(SP)
the actual SP should have been rs.50
therefore the loss% is (50-20)/50
=60%

2.
let on toffee cost rs.1
4 toffees cost rs.4
he sells 3 toffees for rs.4
the actual SP should only have been rs.3
hence his profit %= (4-3)/3
=33.33%