Class 9 Mathematics Chapter 10: How Quantities Combine: Understanding Data — practice questions with answers
Free practice for Class 9 Mathematics, Chapter 10: How Quantities Combine: Understanding Data. Try the solved questions below, then take a free test with instant marking and explanations.
57 questions13 easy, 28 medium, 16 hardNCERT · CBSE · State boards
Sample questions with solutions
Q1. Find the overall average of weekly averages 12.8, 15.8 and 18 minutes (5 days each), to 2 decimal places.
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Answer: 15.53 (± 0.01)
Why: 46.6 ÷ 3 ≈ 15.53 minutes. [p.10]
Why: 46.6 ÷ 3 ≈ 15.53 minutes. [p.10]
Q2. Two equal glasses of lemonade have 10% and 20% jaggery. What is the jaggery concentration when they are mixed?
- 15%
- 30%
- 10%
- 20%
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Answer: A. 15%
Why: Equal quantities → midway. [p.11]
Why: Equal quantities → midway. [p.11]
Q3. What is the formula for the weighted mean of x₁, …, xₙ with weights w₁, …, wₙ?
- (w₁x₁ + w₂x₂ + … + wₙxₙ)/(w₁ + w₂ + … + wₙ)
- (x₁ + x₂ + … + xₙ)/n
- w₁x₁ + w₂x₂ + … + wₙxₙ
- (w₁ + … + wₙ)/(x₁ + … + xₙ)
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Answer: A. (w₁x₁ + w₂x₂ + … + wₙxₙ)/(w₁ + w₂ + … + wₙ)
Why: Each value counts according to its weight. [p.12, p.36]
Why: Each value counts according to its weight. [p.12, p.36]
Q4. In a T20 match a team scores 6 runs in the first over and 12 in the second. What is the run rate after 2 overs?
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Answer: 9 (± 0)
Why: (6 + 12) ÷ 2 = 9. [p.30]
Why: (6 + 12) ÷ 2 = 9. [p.30]
Q5. In 2005 a house used 360 kWh on lighting out of 1000 kWh in total. What percentage was lighting?
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Answer: 36 (± 0)
Why: 360 ÷ 1000 × 100 = 36%. [p.24]
Why: 360 ÷ 1000 × 100 = 36%. [p.24]
Q6. Where is the weighted mean useful? (Tick all that apply)
- Combining marks from tests with different importance
- Finding the concentration of a mixture
- Rating a restaurant on food, service and ambience
- Counting the number of students in a class
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Answer: A. Combining marks from tests with different importance; B. Finding the concentration of a mixture; C. Rating a restaurant on food, service and ambience
Why: Whenever parts differ in size or importance. [p.36]
Why: Whenever parts differ in size or importance. [p.36]
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Frequently asked questions
How many practice questions are there for Class 9 Mathematics Chapter 10: How Quantities Combine: Understanding Data?
57 questions (13 easy, 28 medium, 16 hard). A few are solved on this page; the free test shows the answer and explanation for every question after you submit.
Is this chapter from the NCERT book?
Yes — it follows the NCERT Class 9 Mathematics syllabus, used by CBSE and many state boards.