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Class 11 ch 13 · Class 11 ch 14 · Class 12 ch 13

Statistics and probability: JEE Main and CUET-style questions

Original JEE Main and CUET-style questions on statistics and probability, with a worked solution and the usual trap for each. Tap an option, or type a numerical answer, to check it.

  • 6 questions
  • 3 free
  • 4 multiple choice, 2 numerical value
  • No calculator

Learn the chapters first: Class 11, Statistics · Class 11, Probability · Class 12, Probability.

Questions

Q1

·JEE Main style·Multiple choiceClassical probability

Two fair dice are thrown. The probability that the sum is a prime number is

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Answer: (a) \(\frac{5}{12}\)

Prime sums and their ways: 2 (1), 3 (2), 5 (4), 7 (6), 11 (2). Total 15 of 36, so \(\dfrac{15}{36} = \dfrac{5}{12}\).

Q2

·CUET style·Multiple choiceIndependent events

\(A\) and \(B\) are independent with \(P(A) = \tfrac25\) and \(P(B) = \tfrac14\). Then \(P(A \cup B)\) is

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Answer: (c) \(\frac{11}{20}\)

\(P(A \cap B) = \tfrac25 \cdot \tfrac14 = \tfrac{1}{10}\). \(P(A \cup B) = \tfrac25 + \tfrac14 - \tfrac{1}{10} = \tfrac{8 + 5 - 2}{20} = \tfrac{11}{20}\).

Trap: Adding \(P(A) + P(B) = 13/20\) counts the overlap twice.

Q3

·JEE Main style·Numerical valueVariance

Find the variance of the data \(2, 4, 6, 8, 10\).

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Answer: 8

Mean 6. Squared deviations \(16, 4, 0, 4, 16\), total 40. Variance \(= \dfrac{40}{5} = 8\).

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Next steps

All questions are original, written by CBSE Math Revision in the style of each exam; none are taken from NTA, IIT, CBSE or NCERT papers. Every answer was checked twice: by a computer re-solve and by hand. No calculator needed. Spotted a mistake? Tell us.