Short Answer TypeTwo coins are tossed simultaneously 300 times. The frequency of appearing:
(i) both heads : 75
(ii) one head : 160
(iii) No head : 65
Find the probability of occurrence of each of these events.
Three coins are tossed simultaneously 250 times. The distribution of various outcomes is listed below:
(i) Three tails : 30
(ii) Both tails : 70
(iii) One tail: 90
(iv) No tails : 60
Find the respective probability of each event and check that the sum of all the probabalities is
The weekly pocket expenses of students are given below. Find the probability that the weekly pocket expenses of a student are:
(i) र 59
(ii) more than र 59
(iii) less than र 59
|
Pocket expenses (in र) |
No. of students |
|
45 |
7 |
|
40 |
4 |
|
59 |
10 |
|
71 |
6 |
|
58 |
3 |
|
63 |
8 |
|
65 |
1 |
The percentage of marks obtained by a student in the monthly unit tests are given below:
|
Unit test |
No. of marks obtained |
|
I |
76 |
|
II |
52 |
|
III |
60 |
|
IV |
95 |
|
V |
43 |
Based on this data, find the probability that the
(a) student gets less than 60% marks in a unit test
(b) student gets at least 60% marks in a unit test
The weights of 60 persons in a group are given below:
|
Weight (in kg) |
No. of persons |
|
60 |
5 |
|
61 |
18 |
|
62 |
4 |
|
63 |
16 |
|
64 |
5 |
|
65 |
12 |
Find the probability that a person selected at random has
(a) weight less than 70 kg
(b) weight between 61 and 64 kgs
(c) weight equal to more than 64 kg
Solution not provided.
Ans. (a) 1 (b) 
(c) 
In a survey of 200 men, it was found that 65 men take only coffee, 35 take only tea, 25 donot take either and the rest take both coffee and tea. Find the probability that a man selected at random:
(a) takes coffee
(b) takes only tea
Over the past 200 working days, the number of defective parts produced by a machine are given in the following table:
|
No. of defective parts |
Day |
|
0 |
50 |
|
1 |
32 |
|
2 |
22 |
|
3 |
18 |
|
4 |
12 |
|
5 |
12 |
|
6 |
10 |
|
7 |
10 |
|
8 |
10 |
|
9 |
8 |
|
10 |
6 |
|
11 |
6 |
|
12 |
6 |
|
13 |
6 |
Determine the probability that tomorrow’s output will have not more than 5 defective parts.
In a mathematics test, 90 students obtained (out of 100) the marks given in the following table:
|
Marks |
No. of students |
|
1-20 |
8 |
|
21-40 |
12 |
|
41-50 |
15 |
|
51-60 |
20 |
|
61-70 |
13 |
|
71-80 |
17 |
|
81-90 |
05 |
Find the probability:
(i) a student obtained less than 41,
(ii) a student obtained more than 50,
(iii) a student obtained between 41 and 80.
The data regarding the number of children in a house of a colony which has 250 houses was collected and is recorded below. The houses with number of children are recorded below:
|
No. of children |
No. of houses |
|
1 child |
48 |
|
2 boys |
72 |
|
2 girls |
63 |
|
1 boy and 1 girl |
55 |
|
No child |
10 |
One house is selected at random. What is the probability that it is a house which has
(a) 2 boys?
(b) more than one child?
(c) no children at all?
Fill In the Blanks
Switch
