Question

A number is increased by 20% an then decreased by 10% .Find the net increase or decrease per cent?

Answer 1

Let the number be 100
After Increasing,100+20=120
After Discount,120-12=108
So,Net increase=(108-100)=8%

Answer 2

Let the number be y

Find the number after 20% increased:

20% x y= 0.2(y) = 0.2y

y + 0.2y = 1.2y

Find the number after 10% decreased:

10% x (1.2y) = 0.1(1.2y) = 0.12y

1.2y - 0.12y = 1.08y

Find the net increase:

increased = 1.08y - y = 0.08y

percentage increased = 0.08y/y x 100 = 8%

Answer: The net increase is 8%