Question

The strength of a school increased by 20% in 1 year and decreased by 20% in the next year . is the final strength greater or less than the original one and by how much percent.

Answer 1

Lesser than 4 percent if the school strength is 100

Answer 2

let the original strength be x
increased = 20/100 × x
= x/5

Strength after increasing = x + x/5
= (5x+x)/5
= 6x/5

next year decrease in strength = 20%
decresed = (20/100) × (6x/5 )
= 6x/25

strength after decreasing = 6x/5 - 6x/25
= (30x-6x)/25
= 24x/25

therefore final strength is decresed
amount decreased = x - 24x/25
= (25x-24x)/25
= x/25

percent decreased =( x/25 ÷ x ) × 100%
= x/25 × 1/ x ×100
= 4%

Therefore strength decreases by 4%

Hope this help you...