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Vidaara.orgClass 7 · Mathematics
CodeVID-M07-11-SAM-01
Random Sampling & Inferences - Assignment
Chapter: Statistics (Measures of Center & Variability)
Topic: Random Sampling & Population Inferences
Maximum Marks: 35
Time: 75 minutes
Name: ____________________ Roll No.: __________ Date: ____________

General Instructions

  • All questions are compulsory.
  • Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
  • Show all working for Sections B, C and D. Only final answers are given at the end — for full solutions, raise your doubts with your teacher.
Section A — Multiple Choice Questions 5 × 1 = 5 marks
1.
The entire group studied is the:
  • A.sample
  • B.population
  • C.survey
  • D.mean
2.
A part of the population used for study is a:
  • A.population
  • B.sample
  • C.census
  • D.mode
3.
A random sample gives each member:
  • A.no chance
  • B.an equal chance
  • C.a double chance
  • D.a fixed turn
4.
Larger samples generally give ___ inferences.
  • A.less reliable
  • B.more reliable
  • C.biased
  • D.no
5.
A sample that misrepresents the population is:
  • A.random
  • B.biased
  • C.fair
  • D.large
Section B — Short Answer (2 marks) 4 × 2 = 8 marks
6.
What is the entire group studied called?
7.
What is a part of the population used for study?
8.
A fair sample where everyone has an equal chance is:
9.
Do larger samples generally give more reliable results?
Section C — Short Answer (3 marks) 4 × 3 = 12 marks
10.
In a sample of $50$ students, $30$ like maths. Estimate the percentage in the population who like maths.
11.
A sample of $200$ has $40$ defective items. Estimate the percentage defective.
12.
Why is a random sample preferred?
13.
From a sample of $100$ voters, $55$ support a plan. Estimate support in a town of $10000$.
Section D — Long Answer (5 marks) 2 × 5 = 10 marks
14.
In a random sample of $80$ light bulbs, $4$ are defective. Estimate how many would be defective in a batch of $2000$.
15.
A survey of $250$ people finds $150$ prefer tea. Estimate how many of a town of $20000$ prefer tea, and explain why the sample must be random.

Answer Key

Section A — Multiple Choice Questions
  1. (B) population
  2. (B) sample
  3. (B) an equal chance
  4. (B) more reliable
  5. (B) biased
Section B — Short Answer (2 marks)
  1. The population.
  2. A sample.
  3. Random.
  4. Yes.
Section C — Short Answer (3 marks)
  1. $60\%$.
  2. $20\%$.
  3. It is unbiased and representative.
  4. $5500$.
Section D — Long Answer (5 marks)
  1. $100$.
  2. $12000$; a random sample avoids bias, so the estimate fairly represents the whole town.
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