Statistics — Important Questions
13 hand-picked CBSE Class 10 Maths important questions for Statistics, each with a full model answer — the formats and topics most likely to appear in your board exam.
- 13
- Questions
- 6
- Question types
- 32
- Total marks
- ₹0
- With answers
For grouped data: Mean (assumed-mean method), Median , Mode . The empirical relation is .
About Statistics
This chapter is about the three measures of central tendency for grouped (continuous) data: mean, median and mode. It is a scoring, formula-driven chapter worth roughly 6-8 marks, usually including a case-study and a 5-mark question, often with a missing-frequency twist. Identify the correct class first (median class = the class where cumulative frequency first reaches ; modal class = the class with the highest frequency) before substituting into the formula.
Key concepts & formulas
Take an assumed mean (a convenient class mark), compute , then . The direct method gives the same answer, where is the class mark.
, where lower limit of the median class, , cumulative frequency of the class before the median class, frequency of the median class, class width.
, where lower limit of the modal class (highest-frequency class), its frequency, frequency of the preceding class, frequency of the following class, class width.
For a moderately skewed distribution, . If any two are known, the third can be estimated. The median can also be read as the -coordinate where the two ogives intersect.
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Important questions with answers
Try each on paper first, then reveal the model answer to check your method.
| Question type | Count | Marks |
|---|---|---|
| MCQ | 4 | 1 |
| Assertion–Reason | 1 | 1 |
| Very Short | 2 | 2 |
| Short Answer | 3 | 3 |
| Long Answer | 2 | 5 |
| Case-based | 1 | 4 |
Multiple-choice questions (1 mark)
The class mark of the class interval – is:
- (a)
- (b)
- (c)
- (d)
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Answer: (a)
Class mark
For a distribution, the median is and the mean is . Using the empirical relationship, the mode is:
- (a)
- (b)
- (c)
- (d)
Which measure of central tendency for grouped data can be obtained graphically as the -coordinate of the point of intersection of the two ogives?
- (a)
Median
- (b)
Mean
- (c)
Mode
- (d)
Range
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Answer: (a) Median
The -coordinate of the point where the 'less than' and 'more than' ogives intersect gives the median of the data.
For the distribution below, the sum of the lower limits of the median class and the modal class is:
| Class | 0–5 | 5–10 | 10–15 | 15–20 | 20–25 |
|---|---|---|---|---|---|
| Frequency | 10 | 15 | 12 | 20 | 9 |
- (a)
- (b)
- (c)
- (d)
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Answer: (a)
Cumulative frequencies: The c.f. first reaches in class –, so the median class is – (lower limit ). The highest frequency is in –, so the modal class is – (lower limit ). Sum
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Practise free with the AI tutor →Assertion–Reason questions (1 mark)
Assertion (A): The median of a grouped frequency distribution can be found graphically.
Reason (R): The -coordinate of the point of intersection of the 'less than' and 'more than' ogives gives the median.
- (a)
Both A and R are true and R is the correct explanation of A
- (b)
Both A and R are true but R is not the correct explanation of A
- (c)
A is true but R is false
- (d)
A is false but R is true
Show model answer
Answer: (a) Both A and R are true and R is the correct explanation of A.
The median can indeed be found graphically, precisely by the ogive-intersection method described in R, which is why R correctly explains A.
Very short answer questions (2 marks)
The mean of observations is . If one observation is removed, the mean of the remaining observations becomes . Find the value of the removed observation.
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Sum of observations
Sum of remaining observations
Removed observation
For the following distribution, write the median class and the modal class.
| Class | 0–10 | 10–20 | 20–30 | 30–40 | 40–50 |
|---|---|---|---|---|---|
| Frequency | 5 | 8 | 15 | 7 | 5 |
Show model answer
Cumulative frequencies: The c.f. first reaches in class –, so the median class is –.
The highest frequency is (class –), so the modal class is also –.
Short answer questions (3 marks)
Find the mean daily wage from the following data.
| Daily wage (Rs) | 100–120 | 120–140 | 140–160 | 160–180 | 180–200 |
|---|---|---|---|---|---|
| No. of workers | 12 | 14 | 8 | 6 | 10 |
Find the mode of the following distribution of the ages of patients admitted to a hospital.
| Age (years) | 0–10 | 10–20 | 20–30 | 30–40 | 40–50 |
|---|---|---|---|---|---|
| No. of patients | 8 | 16 | 36 | 34 | 6 |
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The highest frequency is , so the modal class is –.
Here
The median of the following distribution is and the total frequency is . Find the missing frequencies and .
| Class | 0–10 | 10–20 | 20–30 | 30–40 | 40–50 | 50–60 |
|---|---|---|---|---|---|---|
| Frequency | 5 | 20 | 15 | 5 |
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Total:
; since the median lies in –, that is the median class (, ).
Then
Long answer questions (5 marks)
For the following frequency distribution, find the mean and the median. Hence, using the empirical relationship, estimate the mode.
| Class | 0–10 | 10–20 | 20–30 | 30–40 | 40–50 |
|---|---|---|---|---|---|
| Frequency | 5 | 8 | 15 | 16 | 6 |
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Mean: class marks Mean
Median: Cumulative frequencies: Median class – ().
Mode (empirical):
The mean of the following distribution is and the sum of all frequencies is . Find the missing frequencies and .
| Class | 0–20 | 20–40 | 40–60 | 60–80 | 80–100 | 100–120 |
|---|---|---|---|---|---|---|
| Frequency | 5 | 10 | 7 | 8 |
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Total: …(1)
Class marks:
Mean …(2)
From (1), Substituting: Then
Case-based questions (4 marks)
A company tested the life (in hours) of electric bulbs. The results are shown below.
| Life (hours) | 300–400 | 400–500 | 500–600 | 600–700 | 700–800 |
|---|---|---|---|---|---|
| No. of bulbs | 14 | 56 | 60 | 40 | 30 |
(i) Write the modal class.
(ii) Write the median class.
(iii) Find the median life of the bulbs.
Show model answer
(i) Highest frequency is (class –), so the modal class is –.
(ii) Cumulative frequencies: The c.f. first reaches in –, so the median class is –.
(iii)
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