Percentage Mcqs

When a number is first increased by 10 % and then reduced by 10 % the number:__________?

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When a number is first increased by 10 % and then reduced by 10 % the number:__________?

A. does not change
B. decreased by 1 %
C. increased by 1 %
D. None of these
Explanation:
Let the given number be x
Increased Number = (110% of x)
= (110/100 × x) = (11x/10)
Finally reduced number = (90 % of 11x/10)
= (90/100 × 11x/10) = 99x/100
Decrease = (x – 99x/100) = x/100
Decrease % = (x/100 × 1/x × 100)% = 1 %

If the side of a square is increased by 25 %. Then its area is increased by:__________?

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If the side of a square is increased by 25 %. Then its area is increased by:__________?

A. 25 %
B. 55%
C. 40.5 %
D. 56.25 %
Explanation:
Let the side of the square be x units.
Then it’s area = x2 sq. Units
Side of new square = 125 % of x = (125/100 × x)units = 5x/4 units
New area = (5x/4 × 5x/4)sq.units = 25×2/16 Sq.units
Increase in area = (25×2/16 – x2) = 9×2/16 Sq.Units
Increase % = (9×2/16 × 1/x2 × 100)%
= 225/4 % = 56.25 %

A typist uses a paper 30 cm by 15 cm. He leaves a margin of 2.5 cm at the top as well as at the bottom and 1.25 cm on either side. What percentage of paper area is approximately available for typing?

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A typist uses a paper 30 cm by 15 cm. He leaves a margin of 2.5 cm at the top as well as at the bottom and 1.25 cm on either side. What percentage of paper area is approximately available for tyg?

A. 65 %
B. 70 %
C. 80 %
D. 60%
Explanation:
Total Area of the Paper = (30 × 15) Sq.cm = 450 Sq.cm
Area Used = [(30-5)×(15-2.5) ]Sq.cm
= (25 × 12.5) Sq.cm = (25 x 25/2) Sq.cm = 625/2 cm2
Percentage are Used by = (625/2× 1/450×100) %
= 69.4 % = 70 % nearly

The length of a rectangle is increased by 10 % and breadth decreased by 10 % Then the area of a new rectangle is:_________?

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The length of a rectangle is increased by 10 % and breadth decreased by 10 % Then the area of a new rectangle is:_________?

A. neither increased nor decreased
B. increased by 1 %
C. decreased by 1 %
D. decreased by 10 %
Explanation:
Let original length = l units and original breadth = b units
Then original Area = lb sq. Units
New length = (110/100 l) units = (11 l)/10 units
New breadth = (90/100 b) units = (9 l)/10 units
New area = (11l/10 × 9b/10) sq. Units = 99lb/100 sq. units
Decrease in area = (lb- 99lb/100)sq units = lb/100 sq. units
Decrease in area = (lb/100 × 1/lb ×100) % = 1 %
Decrease by = 1 %

A and B are two fixed points 5 cm apart and c is a point on AB such that AC = 3 cm. If the length of AC is increased by 6 % the length of CB is decreased by:_________?

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A and B are two fixed points 5 cm apart and c is a point on AB such that AC = 3 cm. If the length of AC is increased by 6 % the length of CB is decreased by:_________?

A. 6 %
B. 7 %
C. 8 %
D. 9 %
Explanation:
AC = 3cm, CB = (5 – 3)cm = 2 cm
New length AC = 106 % of 3 cm
= (106/100 ×3) cm = 3.18 cm.
New length CB = (5 – 3.18) cm = 1.82 cm
CB Decreased on 2cm = (2 – 1.82)cm = 0.18cm
CB Decrease % = (0.18/2 ×100) % = 9 %

5 % of the income of A is equal to 15 % of the income of B and 10 % of the income of B is equal to 20 % of the income of c. If the income of C is Rs. 2000. What is the total income of A, B and C?

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5 % of the income of A is equal to 15 % of the income of B and 10 % of the income of B is equal to 20 % of the income of c. If the income of C is Rs. 2000. What is the total income of A, B and C?

A. Rs. 14000
B. Rs 16000
C. Rs. 18000
D. Rs. 12400
Explanation:
10/100 × B = 20/100 × c
=>B = 2c =>B = (2 × 2000) = 4000
5/100 × A = 5/100 × B =>A = 3B = (3 × 4000) = 12000
(A + B + C) = Rs (12000 + 4000 + 2000) = Rs. 18000