Paper 4: Fundamentals of Business Mathematics & Statistic

FUNDAMENTALS OF BUSINESS MATHEMATICS AND STATISTICS I 9.21

Example 30 :
A class consists of 100 students, 25 of them are girls and 75 boys, 20 of them are rich and remaining poor, 40
of them are fair complexioned. What is the probability of selecting a fair complexsioned rich girl?
Solution:

Probability of selecting a fair complexioned student = =100 540 2=

Probability of selecting a rich student =100 520 1=

Probability of selecting a girl =100 425 1=

Since the events are independent, by multiplication rule of probability, the

probability of selecting a fair complexioned rich girl = × × =^2 5 5 4 1001 1 2 =0.02

Example 31 :
Three groups of workers contain 3 men and one woman, 2 man and 2 women, and 1 man and 3 woman
respectively. One worker is selected at random from each group. What is the probability that the group
selected consists of 1 man and 2 woman?

Solution:
There are three possibilities :
(i) Man is selected from the first group and women from second and third groups; or
(ii) Man is selected from the second groups and women from first and third groups; or
(iii) Man is selected from the third groups and women from first and second groups.
∴ the probability of selecting a group of one man & two woman
3 2 3 2 1 3 1 1 2
= 4 4 4 4 4 4 4 4 4 ́ ́ + ́ ́ + ́ ́

18 6 2 13

=64 64 64 32+ + =.