Page 2 - Worksheet- Ch-15-Probability

(i)white

(ii)red or black

(iii)not-red

15. 1500 families with 2 children were selected randomly and the following data was recorded: 3

No of girls 0 1 2
No of families 211 814 475
If a family is chosen at random, find the probability that it has
a) at most one girl
b) at least one girl
c) no girl
16. 30 plants were planted in each school out of 12 schools. After a month the 3
number of plants that survived are given below:
School: 1 2 3 4 5 6 7 8 9 10 11 12
Number of 22 15 12 24 27 10 13 22 17 9 20 25
plants
survived:
What is the probability of survival of
i. more than 20 plants in a school
ii. less than 10 plants in a school
iii. exactly 22 plants in a school
17. Three coins are tossed simultaneously 200 times with the following frequencies 4
of different outcomes.
Outcome: 3 heads 2 heads 1 head 3 tails
Frequency: 24 70 75 31
Compute the probability of getting
(i)less than 2 heads
(ii)3 heads
(iii)no head
(iv)at least 1 head
18. Cards with numbers 1, 2, 3, ........, 100 are placed in a box and mixed 4
thoroughly. One card is drawn. What is the probability that the card drawn is
i. a prime number less than 30.
ii. a multiple of 5 and 7
iii. a multiple of 5 or 7
iv. an even number
19. An organisation selected 2400 families at random and surveyed them to 4
determine a relationship between income level and the number of vehicles in a
family. The information gathered is listed in the table below:

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