Chapter 8 · Class 8 CBSE · MCQ Test
Comparing Quantities MCQ Test — Class 8 CBSE
Practice 10 multiple-choice questions with instant answer reveal and explanations.
Comparing Quantities — MCQ Questions
1A shopkeeper first increases the price of an item by 20% and then decreases the new price by 20%. Which of the following statements is true about the final price compared to the original price?
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Answer: The final price is less than the original price.
Hint: Consider a starting price, say ₹100, and apply the changes step-by-step. Remember, the percentage decrease is applied to the *new* increased price, not the original.
Solution:
Let the original price be ₹100.
Increasing by 20%: New price = 100 + (20/100) × 100 = 100 + 20 = ₹120.
Decreasing the new price by 20%: Decrease amount = (20/100) × 120 = ₹24.
Final price = 120 - 24 = ₹96. Since ₹96 < ₹100, the final price is less than the original price.
2A vendor sells a bicycle. Which of the following conditions must be true for the vendor to make a profit?
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Answer: Selling Price (SP) > Cost Price (CP)
Hint: Profit occurs when you sell an item for more than what you paid for it.
Solution:
Profit is defined as the excess amount received from selling an item over its cost.
Mathematically, Profit = Selling Price (SP) - Cost Price (CP).
For profit to be positive (i.e., a profit is made), SP must be greater than CP.
3In a school, 40% of the students are girls. If the total number of girls is 240, what is the total number of students in the school?
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Answer: 600
Hint: If 40% of the total represents 240 students, you can set up an equation to find the total.
Solution:
Let the total number of students be 'X'.
According to the problem, 40% of X is 240.
This can be written as (40/100) × X = 240.
Solving for X: X = (240 × 100) / 40 = 6 × 100 = 600.
4Rahul bought a book for ₹200 and sold it for ₹240. He calculated his profit percentage as (₹40 / ₹240) × 100%. Which of the following statements correctly identifies Rahul's mistake?
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Answer: Both B and C are correct.
Hint: Profit percentage is always calculated on the Cost Price (CP), not the Selling Price (SP).
Solution:
Rahul's profit amount is ₹240 - ₹200 = ₹40, which is correct.
Profit percentage is calculated as (Profit / Cost Price) × 100%.
Rahul used the Selling Price (₹240) in the denominator instead of the Cost Price (₹200).
The correct calculation should be (₹40 / ₹200) × 100% = 20%.
5A shop offers a discount on an item. Which of the following statements correctly describes the relationship between the Marked Price (MP), Selling Price (SP), and Discount (D)?
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Answer: D = MP - SP
Hint: Discount is the reduction offered on the listed price to arrive at the selling price.
Solution:
The Marked Price (MP) is the price listed on the item.
The Discount (D) is the reduction offered on the MP.
The Selling Price (SP) is the price the customer actually pays after the discount.
Therefore, Selling Price = Marked Price - Discount, or SP = MP - D.
Rearranging this, we get Discount = Marked Price - Selling Price, or D = MP - SP.
6A washing machine is priced at ₹15,000. If 18% GST is charged on it, which of the following expressions correctly calculates the final amount a customer has to pay?
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Answer: ₹15,000 + (18/100) × ₹15,000
Hint: GST (Goods and Services Tax) is an additional charge added to the original price of an item.
Solution:
The price of the washing machine is ₹15,000. This is the base price.
GST is a tax added to this base price.
Amount of GST = (GST Rate / 100) × Original Price = (18/100) × ₹15,000.
Final amount to pay = Original Price + Amount of GST.
Therefore, Final amount = ₹15,000 + (18/100) × ₹15,000.
7Simple Interest (SI) is calculated using the formula SI = (P × R × T) / 100. Which of the following statements is TRUE about Simple Interest?
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Answer: SI depends on the principal amount, rate of interest, and time period.
Hint: Look at the variables directly involved in the formula for Simple Interest.
Solution:
The formula for Simple Interest is SI = (P × R × T) / 100.
P stands for Principal (the initial sum of money).
R stands for Rate of interest (per annum).
T stands for Time (in years).
Therefore, Simple Interest directly depends on the Principal, Rate, and Time.
Option D describes Compound Interest, not Simple Interest.
8After a 20% reduction in its price, a TV now costs ₹16,000. What was the original price of the TV?
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Answer: ₹20,000
Hint: If the price was reduced by 20%, the current price represents (100 - 20)% of the original price.
Solution:
Let the original price be 'X'.
A 20% reduction means the TV is now sold at (100 - 20)% = 80% of its original price.
So, 80% of X = ₹16,000.
(80/100) × X = 16,000.
X = (16,000 × 100) / 80 = 200 × 100 = ₹20,000.
9Shop A offers a flat 25% discount on all items. Shop B offers a 'Buy 2 Get 1 Free' scheme on items of the same price. Which shop offers a better discount for a customer buying 3 items?
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Answer: Shop B
Hint: For 'Buy 2 Get 1 Free', you pay for 2 items but get 3. Calculate the effective discount percentage for Shop B.
Solution:
Shop A: Offers a flat 25% discount.
Shop B: 'Buy 2 Get 1 Free'
If a customer buys 3 items (the total received), they pay for 2 items. Let the price of one item be ₹P.
The actual value of 3 items = 3P. The customer pays = 2P. Discount amount = 3P - 2P = P.
Discount percentage = (Discount amount / Actual value of items received) × 100% = (P / 3P) × 100% ≈ 33.33%.
Comparing discounts: Shop A offers 25%, while Shop B offers approximately 33.33%. Therefore, Shop B offers a better discount.
10A shopkeeper sold a defective fan for ₹1,200, incurring a loss of 20%. What was the cost price of the fan?
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Answer: ₹1,500
Hint: If there was a 20% loss, the selling price represents (100 - 20)% of the cost price.
Solution:
Let the Cost Price (CP) be 'X'.
Loss percentage = 20%.
This means the Selling Price (SP) is (100 - 20)% = 80% of the Cost Price.
So, 80% of X = ₹1,200.
(80/100) × X = 1,200.
X = (1,200 × 100) / 80 = 1,500.
The cost price of the fan was ₹1,500.
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Tips for Comparing Quantities MCQs
- 1Read each question carefully and identify what is being asked before looking at the options.
- 2Try to solve the problem mentally or on paper first, then match your answer with the options.
- 3Use elimination — rule out clearly wrong options to improve your chances even when unsure.
- 4Check units, signs, and edge cases — these are common traps in Comparing Quantities MCQs.
- 5Review your mistakes after completing the test to build lasting understanding.
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