(Q11) 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 figure), and these are equally likely outcomes. What is the probability that it will point at

(i) 8 ?

(ii) an odd number ?

(iii) a number greater than 2 ?

(iv) a number less than 9 ?

12345678

Answer :

Number of total outcomes are =

(i) Number of outcomes favourable to 8 =

∴ P(8) =
No. of favourable outcomes
No. of total outcomes
 =

(ii) Number of 'odd numbers' on the spinning wheel =

∴ Number of outcomes favourable to an odd number.

∴ Probability of getting an odd number =
No. of favourable outcomes
No. of total outcomes
 =
=
1

(iii) Number greater than 2 are

Number of outcomes favourable to 'greater than 2' are = .

Probability of pointing a number greater than 2

P(E) =
No. of favourable outcomes
No. of total outcomes
 =
=
3

(iv) Number less than 9 are:

∴ Number of outcomes favourable to pointing a number less than 9 =

∴ Probability of a number less than 9

P(E) =
No. of favourable outcomes to less than 9
No. of total outcomes
 =
=