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Alternative way: Unitary method
Quick Check
The team’s win percentage is 60, which means they win 60
matches when they play 100 matches. 1. Find:
100 (a) 2.5% of 200 bulbs
So, they win 1 match when they play matches. 2
60 (b) 16 % of 600 L
3
Thus, they win 12 matches when they play 100 × 12 = 20 2. 15% of which number is 30?
matches. 60 3. A real estate agent receives `50,000
Increase or Decrease in Per cent as commission, which is 4% of the
selling price. At what price does
Sometimes we need to know the increase or decrease in a the agent sell the property?
certain quantity as a percentage.
Change in value (increase or decrease)
Percentage increase/decrease = × 100%
Original value (or baase)
Example 3: An Android handset when launched was sold for `48,000. After six months, it was sold
for `45,600. Determine the percentage reduction in the price of the mobile phone.
Solution: The initial price of the handset = `48,000

The price of the handset after six months = `45,600
Reduction in the price of the mobile phone = `48,000 – `45,600 = `2,400
Decrease in price 2400
Percentage decrease in price = × 100% = × 100% = 5%
Initial price 48000
Example 4: Raman weighed 40 kg two months ago. Today, he weighs 46 kg. Find the percentage
gain in his weight. He starts physical exercises to lose 10% of his weight in 1 month. What will be
his weight if he achieves his goal?
Solution: Two months ago, Raman’s weight = 40 kg
Current weight = 46 kg

Weight gain = 46 kg – 40 kg = 6 kg
6 kg
Percentage weight gain = × 100% = 15%
40 kg
After 1 month, Raman’s weight = 46 kg – 10% of 46 kg
 10 
= 46 kg –   100 × 46 kg = 46 kg – 4.6 kg = 41.4 kg


Finding the Original Amount before a Percentage Change

Example 5: If Chameli had `6000 left after spending 75% of her money, how money much did she
have in the beginning?
Solution: Let the initial amount Chameli had be `x.
3
Her expenses = 75% of `x = 75 of x = ` x
100 4
Money left with Chameli = Initial amount – expenditure
3 1
⇒ `6000 = `x – ` x ⇒ `6000 = ` x
4 4
⇒ x = `(6000 × 4) = `24,000

Thus, Chameli had `24,000 in the beginning.

169 Comparing Quantities