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- Question
- 72% of the students of a certain class took Biology and 44% took Mathematics. If each student took Biology or Mathematics and 40 took both. The total number of students in the class was?
Options- A. 200
- B. 240
- C. 250
- D. 320
- Correct Answer
- 250
ExplanationLet the total number of students be 100
Then, n(A ? B) = n(A) + n(B) - n(A ? B) = (72 + 44 - 100)% = 16%
Now,16% of N = 40
? (16 x N) / 100 = 40
? N = (100 x 40) / 16 = 250 - 1. The boys and girls in a collage are in ratio 3 : 2. If 20% of the boys and 25% of the girls are adults, the percentage of students who are not adults is?
Options- A. 58%
- B. 67.5%
- C. 78%
- D. 82.5% Discuss
- 2. A mixture of 40 litres of milk and water contains 10% water. How much water should be added to this so that water may be 20% in the new mixture?
Options- A. 4 litres
- B. 5 litres
- C. 6.5 litres
- D. 7.5 litres Discuss
- 3. If the numerator of a fraction is increased by 20% and he denominator be diminished by 10%, the value of the fraction is 16/21. The original fraction is?
Options- A. 3/5
- B. 4/7
- C. 2/3
- D. 5/7 Discuss
- 4. The price of an article has been reduced by 25%. In order to restore the original price, the new price must be increased by?
Options- A. 331/3%
- B. 111/9%
- C. 91/11%
- D. 662/3% Discuss
- 5. A man spends 75% of his income. This income is increased by 20% and he increased his expenditure by 10%. His savings are increased by?
Options- A. 10%
- B. 25%
- C. 371/2%
- D. 50% Discuss
- 6. If the side of a square is increased by 30%, its area is increased by?
Options- A. 9%
- B. 30%
- C. 60%
- D. 69% Discuss
- 7. The radius of circle is increased by 1%. What is the increased percent in its area?
Options- A. 1%
- B. 1.1 %
- C. 2%
- D. 2.01 % Discuss
- 8. The length and breadth of square are increased by 30% and 20% respectively. The area of the rectangle so formed exceeds the area of the square by?
Options- A. 20%
- B. 36%
- C. 50%
- D. 56% Discuss
- 9. The length of a rectangle is increased by 60%. By what per cent would the width have to be decreased to maintain the same area?
Options- A. 371/2%
- B. 60%
- C. 75%
- D. None of these Discuss
- 10. The price of coffee is increased by 15% and a house wife reduced her consumption of coffee by 15% and hence her expenditure on coffee?
Options- A. Remains unchanged
- B. Increased by 4%
- C. Decreased by 4%
- D. Decreased by 2.25% Discuss
Percentage problems
Search Results
Correct Answer: 78%
Explanation:
Suppose boys = 3N and girls = 2N
Not adults = (80% of 3N) + (75% of 2N) = (12N/5 + 3N/2) = 39N/10
? Required percentage = (39N/10 / 1/5N) x 100 % = 78%
Correct Answer: 5 litres
Explanation:
? Milk = 90% 0f 40 = 36 litres and water = 4 litres.
Let L litre water to be added in order to make 20% water in new mixture.
? {(4 + L) / (40 + L)} x 100 = 20
? 20 x (40 + L) = 100 x (4 + L)
? 80 x L = 400
? L = 5 litres .
Correct Answer: 4/7
Explanation:
Let the original fraction be p/q
Now, (120% of p) / (90% of q) = 16 / 21
? 4p / 3q = 16/21
? p / q = (16/21) x (3/4) = 4 / 7
Correct Answer: 331/3%
Explanation:
Let original price = Rs. 100
Reduced price = Rs. 75
Increase on Rs. 75 = Rs. 25
Increase on Rs. 100 = (25 x 100)/75 % = 331/3 %
Correct Answer: 50%
Explanation:
Let income = Rs. 100
Then expenditure = Rs. 75 and saving = Rs. 25
New expenditure = 110% of Rs. 75 = Rs. 165 / 2
New saving = Rs. (120 - 165/2) = Rs. 75/2
Increase in saving = Rs. (75/2 - 25) = Rs. 25/2
? Increase% = (25/2) x (1/25) x 100% = 50%
Correct Answer: 69%
Explanation:
Let side of square = 100 cm
Area = (100 x 100)cm2 = 10000 cm2
New area = (130 x 130)cm2 = 16900 cm2
Increase in area = (6900 / 10000) x 100% = 69%
Correct Answer: 2.01 %
Explanation:
Let radius of circle = 100 m
New radius = 101 m
original area = [? x (100)2 ]m2
New area = [? x (101)2 ]m2
Increase% = [? x {(101)2 - (100)2} / { ? x (100)2} ] x 100 %
= 201 / 100% = 2.01%
Correct Answer: 56%
Explanation:
Let length of square = 100 m and breadth of square = 100 m
Area = (100 x 100) m2 = 10000 m2
New length = 130 m and breadth = 120 m
New area of rectangle = (130 x 120) m2 = 15600 m2
Increase % = (5600 / 10000) x 100 % = 56%
Correct Answer: 371/2%
Explanation:
Let length of a rectangle = 100 m,
Breadth = 100 m
New length = 160 m,
New breadth = B meters
Then, 160 x B = 100 x 100
? B = (100 x 100) / 160 = 125/2
Decrease in breadth = (100 - 125/2)% = 371/2%
Correct Answer: Decreased by 2.25%
Explanation:
Consumption Decreases = (common %)2/100
= 225/100
= 2.25%.
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