2025 · Standard · Set 6 · Part 3·Q21·2 marks

Introduction to Trigonometry

Question

A box contains 120 discs, which are numbered from 1 to 120. If one disc is drawn at random from the box, find the probability that
(i) it bears a 2-digit number
(ii) the number is a perfect square.

Approach

Total discs = 120. (i) Two-digit numbers (10 to 99) = 90; P = 90/120 = 3/4. (ii) Perfect squares in 1-120 are 1,4,9,16,25,36,49,64,81,100 = 10; P = 10/120 = 1/12.

Step-by-step working

  1. 1

    P(2-digit number) = 90/120 or 3/4

    1 mark
  2. 2

    P(perfect square) = 10/120 or 1/12

    1 mark

Concepts used

probabilitytwo-digit numberperfect square

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