Question
30 plants were planted in each school out of 12 schools. After a month the number of plants that survived are given below:
|
School |
Number of plants survived |
|
1 |
22 |
|
2 |
15 |
|
3 |
12 |
|
4 |
24 |
|
5 |
27 |
|
6 |
10 |
|
7 |
13 |
|
8 |
22 |
|
9 |
17 |
|
10 |
9 |
|
11 |
20 |
|
12 |
25 |
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?
Solution
Total number of schools =12
(i) Number of schools in which more than 20 plants survived = 5
∴ Probability of survival of more than 20 plants in a school 
(ii) Number of schools in which less than 10 plants survived = 1
∴ Probability of survival of less than 10 plants in a school = 
(iii) Number of schools in which exactly 22 plants survived = 2
Probability of survival of exactly 22 plants in a school = 
