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Finding the Increase Or Decrease per Cent

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We often come across such information in our daily life as. 
(i) 25% off on marked  prices (ii) 10% hike in the price of petrol 
Let us consider a few such examples. 
Example :  The price of a scooter was Rs. 34,000 last year. It has  increased by 20% this year. What is the price now?
Solution: 
Amita said that she would first find the increase in the price, which is 20% of Rs. 34,000, and then find the new price 
20% of Rs. 34000 = Rs. `20/100 xx 34000`
= Rs. 6800
New price  = Old price + Increase 
= Rs.34,000 + Rs. 6,800 
= Rs. 40,800 
OR 
Sunita used the unitary method. 20% increase means,Rs.100 increased to Rs.120. So, Rs. 34,000 will increase to?
Increased price = Rs. `120/100 xx 34000`
= Rs.40800
Similarly, a percentage decrease in price would imply finding the actual decrease followed by its subtraction the from original price. 
Suppose in order to increase its sale, the price of scooter was decreased by 5%. Then let us find the price of scooter. 
Price of scooter  = Rs. 34000 
Reduction = 5% of Rs. 34000
`= Rs. 5/100 xx 34000 = Rs. 1700`
New price = Old price – Reduction 
= Rs.34000 – Rs. 1700 =Rs. 32300

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