Exercise 14.1, 12

A game of chance consists of spinning an arrow which comes to rest pointing at one of the numbers 1, 2, 3, 4, 5, 6, 7, 8 (see Fig. 14.5 ), and these are equally likely outcomes. What is the probability that it will point at

Class 10 - A game of chance consists of spinning an arrow

(i) 8 ?
(ii) an odd number?
(iii) a number greater than 2?
(iv) a number less than 9?

 

Given:
  • Numbers on the spinner: 1, 2, 3, 4, 5, 6, 7, 8
  • Total outcomes = 8 (since there are 8 numbers)

 

(i) Probability that it points at 8:

  • Favourable outcome = 1 (only the number 8)

Probability (8) = 1/8

(ii) Probability of an odd number:

  • Odd numbers = 1, 3, 5, 7
  • Favourable outcomes = 4

Probability (odd) = 4/8 = 1/2โ€‹

(iii) Probability of a number greater than 2:

  • Numbers greater than 2 = 3, 4, 5, 6, 7, 8
  • Favourable outcomes = 6

Probability (>2) = 6/8 = 3/4

(iv) Probability of a number less than 9:

  • All numbers (1 to 8) are less than 9
  • Favourable outcomes = 8

Probability (<9) = 8/8 = 1

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