This is an extension of 4.7 Successive Changes section in Percentages lesson. The multiplication factors for the respective percentage changes can be successively multiplied.
Example 8
A manufacturer sells a product at a profit of 25% to the stockist, who in turn sells the product at a profit of 20% to a wholesaler, who in turn sells it at a profit of 33.33% to a retailer, who in turn sells it at a profit of 10% to the end customer. By what percentage is the customer's purchase price greater than the cost of manufacturing the product?
Solution
As all the numbers in the question are in percentage terms, we can assume a number. Let the cost of manufacturing the product be Rs. 100.
At each stage, the value of the product is increasing by the said percentage. As the growths are successive, we can multiply them one after the other.
Customer's purchase price was higher by 100220−100×100%=120%
Answer: 120%
Example 9
A trader purchased an item at Rs. 500. The trader then increased the price by 25% and reduced it by 4%. The trader once again increased the price by 25% and reduced it by 4% and then sold the item. What was the overall profit of the trader?
Solution
Like in the previous example, the mark-ups and discount factors can be successively multiplied to arrive at the final selling price.
For the following common types, applicable formulae and their derivation are provided. If you are clear with the concepts detailed, you will be able to derive these formulae in a matter of seconds. Therefore, you needn't memorise them.
6.1 When Discount and Mark up percentages are equal
Let x% be the discount and marked up percentage of the product.
SP=CP(1+100x)(1−100x)
⇒ SP=CP(1−1002x2)
In this scenario, a loss will always be occurred and the loss would equal 100x2%
Example 10
John buys a product at Rs. 500 and marks it up by 15%. After extensive bargaining with a customer, he sells it to her at a discount of 15% on the marked up price. What is the overall percentage of profit or loss incurred by John?
(1) 1.50%
(2) 1.75%
(3) 2.25%
(4) 3.00%
Solution
Directly applying the formula, we get Loss %=100152%=2.25%
Alternatively
SP =500×(1+10015)×(1−10015)=500×(1−1002152)
⇒ SP=500×(1−0.0225)⟶(1)
As SP=CP×(1−Loss%), from equation (1) we get
Loss %=0.0225×100%=2.25%
Answer: (3) 2.25%
6.2 Two products with same SP and same Profit/Loss percentage
When the selling price of two products is the same and one is sold at a profit of x% and the other at a loss of x%, then the two transactions combined would have resulted in a loss of100x2%
Example 11
Pratap trades in motorcycles. On a certain day he sells two motorcycles for Rs. 480 each. If one was sold at a profit of 20% and the other at a loss of 20%, what was his overall profit/loss from the transaction?
Solution
Total Selling Price (SP) =480×2=960
Overall loss =100202%CP=4% of CP =0.04CP
CP−0.04CP=960 ⇒0.96CP=960 ⇒CP=1000
Overall loss =0.04CP=0.04×1000=40
Answer: Loss of Rs. 40
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