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In a pre-primary class… (Class 10 Maths Basic 2025, Q24b)

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MathsCBSE Class 10 · Basic · Board exam 2025, set 430/5/1 · 2 marks · Very short answer

CBSE Class 10 Mathematics Basic 2025: question 24(b)

Set in the CBSE Class 10 board exam of 2025, paper 430/5/1, section B, question 24(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q24(b) · 2 marks · Very short answerProbability

In a pre-primary class, a teacher put cards numbered 20 to 59 in a bowl. A student picked up a card at random and read the number. Find the probability that the number read was (i) a prime number (ii) a perfect square.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 430/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

First count how many cards there are from 20 to 59 (include both ends).

Hint 2

List the primes and the perfect squares in this range carefully, then divide each count by the total.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Total cards numbered 20 to 59 .
    (i) Primes between 20 and 59: 23, 29, 31, 37, 41, 43, 47, 53, 59, i.e. 9 numbers.
    P(prime)

    1 mark

  2. (ii) Perfect squares between 20 and 59: 25, 36, 49, i.e. 3 numbers.
    P(perfect square)

    1 mark

Answer: (i) ; (ii)

Where the marks are

  • Total outcomes 40, counts 9 primes and gets (1 mark)
  • Counts 3 perfect squares and gets (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Probability, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 430/5/1 (Basic): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.