2025 · Standard · Set 5 · Part 1·Q24·2 marks

Triangles

Question

In a pre-primary class, a teacher put cards numbered to 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.

Approach

Total cards = 40. Primes from 20–59 are 23,29,31,37,41,43,47,53: 9 primes, . Perfect squares are 25, 36, 49: 3 squares, .

Step-by-step working

  1. 1

    Count prime numbers: 9 primes in 40 cards

    1 mark
  2. 2

    Count perfect squares: 3 in 40 cards

    1 mark

Concepts used

probabilityprime numbersperfect squarescounting

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