Percentage
- The difference between the value of the number increased by 20% and the value of the number decreased by 25% is 36. Find the number.
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Let the number be x.
∴ (20 + 25)% of x = 36⇒ 45x = 36 100 ⇒ x = 36 × 100 = 80 45 Correct Option: D
Let the number be x.
∴ (20 + 25)% of x = 36⇒ 45x = 36 100 ⇒ x = 36 × 100 = 80 45
- A number is first decreased by 20%. The decreased number is then increased by 20%. The resulting number is less than the original number by 20. Then the original number is
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Effective percentage
= 
- 20 + 20 - 20 × 20 
= – 4% 100
If the number be x, then
4% of x = 20⇒ x × 4 = 20 100 ⇒ x = 20 × 100 = 500 4
Aliter : Using Rule 3,
Let the number be xDecrease % = 202 = 20 100
x – 4% of x = x – 204x = + 20 100
x = 500Correct Option: C
Effective percentage
= - 20 + 20 - 20 × 20 = – 4% 100
If the number be x, then
4% of x = 20⇒ x × 4 = 20 100 ⇒ x = 20 × 100 = 500 4
Aliter : Using Rule 3,
Let the number be xDecrease % = 202 = 20 100
x – 4% of x = x – 204x = + 20 100
x = 500
- A number is increased by x %; to get back to the original number, it is to be reduced by
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Initial value increasing value P × x → increased value → P + Px 100 100 = P 100 + x 100
∴ Required answer= x × 100 % 100 + x Correct Option: B
Initial value increasing value P × x → increased value → P + Px 100 100 = P 100 + x 100
∴ Required answer= x × 100 % 100 + x
- A number is decreased by 10% and the resulting number is again decreased by 20%. What is the final percentage of decrease?
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Effective percentage decrease
= x + y + xy % 100 = - 10 - 20 + (- 10) × (- 20) % 100
= (– 30 + 2)% = –28%Correct Option: D
Effective percentage decrease
= x + y + xy % 100 = - 10 - 20 + (- 10) × (- 20) % 100
= (– 30 + 2)% = –28%
- The price of an edible oil is increased by 25%. To maintain the budget, Sushma reduces the consumption of this oil by 20%. The increase in expenditure due to this edible oil is:
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Cost of edible oil = 100 per kg.
Consumption = 1 kg.
Again,
New price = 125 per kg.
Consumption = 0.8 kg.
Expenditure = Rs. (125 × 0.8) = Rs. 100
OR
Percentage effect= x + y + xy % 100 = 25 - 20 - 25 × 20 % = 0% 100 Correct Option: A
Cost of edible oil = 100 per kg.
Consumption = 1 kg.
Again,
New price = 125 per kg.
Consumption = 0.8 kg.
Expenditure = Rs. (125 × 0.8) = Rs. 100
OR
Percentage effect= x + y + xy % 100 = 25 - 20 - 25 × 20 % = 0% 100
