496. The tax imposed on an article is decreased by 10% and its consumption increases by 10%. Find the percentage change in revenue from it.

1. 1. 10% increase

   
   
   

   2. 2% decrease

   
   
   

   3. 1% decrease

   
   
   

   4. 11% increase

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 3
   Tricky approach
   Required change
   

   =	(10)2	% decrease = 1% decrease
   	100

   Correct Option: C

   Using Rule 3
   Tricky approach
   Required change
   

   =	(10)2	% decrease = 1% decrease
   	100

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497. A number is increased by 20% and then it is decreased by 10%. Find the net increase or decrease per cent.

1. 1. 10% increase

   
   
   

   2. 10% decrease

   
   
   

   3. 8% increase

   
   
   

   4. 8% decrease

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 4,
   Net % change
   

   =		A + B +	AB		%
   			100

   
   Here, A = 20%, B = – 10%
   ∴ Net % change
   

   20 - 10 -	200
   	100

   
   = 10 – 2= 8%
   + ve sign shows increase

   Correct Option: C

   Using Rule 4,
   Net % change
   

   =		A + B +	AB		%
   			100

   
   Here, A = 20%, B = – 10%
   ∴ Net % change
   

   20 - 10 -	200
   	100

   
   = 10 – 2= 8%
   + ve sign shows increase

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498. Salary of a person is first increased by 20%, then it is decreased by 20%. Percentage change in his salary is :

1. 1. 4% decreased

   
   
   

   2. 4% increased

   
   
   

   3. 8% decreased

   
   
   

   4. 20% increased

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 4,
   Change in his salary
   

   =		20 - 20 -	20 × 20		%
   			100

   
   

   =		-	400		% = – 4%
   			100

   
   i.e. 4% decrease
   Note : If A is first increased by x% and then decreased by y% the net % change
   

   =		x - y -	xy		%
   			100

   
   If the result is positive, the change indicates increase and if the result is negative, the change indicates decrease.

   Correct Option: A

   Using Rule 4,
   Change in his salary
   

   =		20 - 20 -	20 × 20		%
   			100

   
   

   =		-	400		% = – 4%
   			100

   
   i.e. 4% decrease
   Note : If A is first increased by x% and then decreased by y% the net % change
   

   =		x - y -	xy		%
   			100

   
   If the result is positive, the change indicates increase and if the result is negative, the change indicates decrease.

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499. An examiner has to secure 40% marks to pass an examination. He secures 180 marks and fails by an equal number of marks. The total number of marks in the examination is

1. 1. 900

   
   
   

   2. 1000

   
   
   

   3. 1050

   
   
   

   4. 800

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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500. An engineering student has to secure 25% marks to pass. He gets 47 and fails by 43 marks. What are the maximum marks of the examination ?

1. 1. 385 marks

   
   
   

   2. 410 marks

   
   
   

   3. 360 marks

   
   
   

   4. 435 marks

   
   
   

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1. View Hint View Answer Discuss in Forum

   Maximum marks of examination = x (let)
   According to the question,
   25% of x = 47 + 43
   

   =	x × 25	= 90
   	100

   
   

   ⇒	x	= 90 ⇒ x = 4 × 90 = 360
   	4

   Correct Option: C

   Maximum marks of examination = x (let)
   According to the question,
   25% of x = 47 + 43
   

   =	x × 25	= 90
   	100

   
   

   ⇒	x	= 90 ⇒ x = 4 × 90 = 360
   	4

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