51. If price of a book is first decreased by 25% and then increased by 20%, the net change in the price of the book will be

1. 1. 10% decrease

   
   
   

   2. 5% decrease

   
   
   

   3. no change

   
   
   

   4. 5% increase

   
   
   

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1. View Hint View Answer Discuss in Forum

   The net change in price
   

   =		25 + 20 -	25 × 20		%
   			100

   
   = (–25 + 20 – 5)% = – 10%
   Negative sign shows decrease.

   Correct Option: A

   The net change in price
   

   =		25 + 20 -	25 × 20		%
   			100

   
   = (–25 + 20 – 5)% = – 10%
   Negative sign shows decrease.

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52. The price of an article is reduced by 25% but the daily sale of the article is increased by 30%. The net effect on the daily sale receipts is

1. 1. 2	1	% increase
      	2

   
   
   

   2. 2	1	% decrease
      	2

   
   
   

   3. 2 % increase

   
   
   

   4. 2% decrease

   
   
   

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1. View Hint View Answer Discuss in Forum

   Let the price of the article be ₹100 and the daily sale be 100 units.
   ∴ Revenue day = 100 × 100 = ₹10000
   New receipts = 75 × 130 = ₹9750
   Decrease = ₹(10000 – 9750) = ₹250
   ∴ % decrease
   

   =	250	× 100 = 2	1	%
   	10000		2

   
   Aliter : Using Rule 5,
   Required change
   

   =		a - b -	ab		%
   			100

   
   

   =		30 - 25 -	30 × 25		%
   			100

   
   

   = 5 -	15	= –2.5%
   	2

   
   

   = 2	1	% decrease.
   	2

   Correct Option: B

   Let the price of the article be ₹100 and the daily sale be 100 units.
   ∴ Revenue day = 100 × 100 = ₹10000
   New receipts = 75 × 130 = ₹9750
   Decrease = ₹(10000 – 9750) = ₹250
   ∴ % decrease
   

   =	250	× 100 = 2	1	%
   	10000		2

   
   Aliter : Using Rule 5,
   Required change
   

   =		a - b -	ab		%
   			100

   
   

   =		30 - 25 -	30 × 25		%
   			100

   
   

   = 5 -	15	= –2.5%
   	2

   
   

   = 2	1	% decrease.
   	2

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53. Two successive price increases of 10% and 10% of an article are equivalent to a single price increase of

1. 1. 19%

   
   
   

   2. 20%

   
   
   

   3. 21%

   
   
   

   4. 22%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 7,
   Tricky approach
   Single equivalent percentage increase in price
   

   =		10 + 10 +	10 × 10		% = 21 %
   			100

   Correct Option: C

   Using Rule 7,
   Tricky approach
   Single equivalent percentage increase in price
   

   =		10 + 10 +	10 × 10		% = 21 %
   			100

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54. The price of an article was first increased by 10% and then again by 20%. If the last increased price be 33, the original price was

1. 1. 30

   
   
   

   2. 27.50

   
   
   

   3. 26.50

   
   
   

   4. 25

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 7,
   Tricky approach
   Effective increase percentage
   

   =		10 + 20 +	20 × 10		% = 32%
   			100

   
   

   ∴ x ×	132	= 33
   	100

   
   

   ⇒ x =	33 × 100	= ₹ 25
   	132

   Correct Option: D

   Using Rule 7,
   Tricky approach
   Effective increase percentage
   

   =		10 + 20 +	20 × 10		% = 32%
   			100

   
   

   ∴ x ×	132	= 33
   	100

   
   

   ⇒ x =	33 × 100	= ₹ 25
   	132

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55. If a number is increased by 20% and the resulting number is again increased by 20%, what per cent is the total increase ?

1. 1. 48%

   
   
   

   2. 44%

   
   
   

   3. 41%

   
   
   

   4. 40%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 7,
   Effective percentage increase
   

   =		20 + 20 +	20 × 20		% = 44%
   			100

   Correct Option: B

   Using Rule 7,
   Effective percentage increase
   

   =		20 + 20 +	20 × 20		% = 44%
   			100

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