1500 families with 2 children were selected randomly, and the following data were recorded:
Number of girls in a family |
2 |
1 |
0 |
Number of families |
475 |
814 |
211 |
Compute the probability of a family, chosen at random, having
(0 2 girls (ii) 1 girl (iii) No girl.
Also check whether the sum of these probabilities is 1.
Three coins are tossed simultaneously 200 times with the following frequencies of different outcomes:
Outcome |
3 heads |
2 heads |
1 head |
No head |
Frequency |
23 |
72 |
71 |
28 |
If the three coins are simultaneously tossed again, compute the probability of 2 heads coming up.
An organisation selected 2400 families at random and surveyed them to determine a relationship between income level and the number of vehicles in a family. The information gathered is listed in the table below:
Monthly income |
Vehicles per family |
|||
(in र) |
0 |
1 |
2 |
Above 2 |
Less than 7000 |
10 |
160 |
25 |
0 |
7000-10000 |
0 |
305 |
27 |
2 |
10000-13000 |
1 |
535 |
29 |
1 |
13000–16000 |
2 |
469 |
59 |
25 |
16000 or more |
1 |
579 |
82 |
88 |
Suppose a family is chosen. Find the probability that the family chosen is
(i) earning र 10000–13000 per month and owning exactly 2 vehicles.
(ii) earning र 16000 or more per month and owning exactly l vehicle.
(iii) earning less than र 7000 per month and does not own any vehicle.
(iv) earning र 13000–16000 per month and owning more than 2 vehicles.
(v) owning not more than I vehicle.
Marks (out of 100) |
Number of students |
0-20 |
7 |
20-30 |
10 |
30-40 |
10 |
40-50 |
20 |
50-60 |
20 |
60-70 |
15 |
70–above |
8 |
Total |
90 |
(i) Find the probability that a student obtained less than 20% in the mathematics test.
(ii) Find the probability that a student obtained marks 60 or above.
To know the opinion of the students about the subject statistics, a survey of 200 students was conducted. The data is recorded in the following table:
Opinion |
Number of students |
like dislike |
135 65 |
Find the probability that a student chosen at random
(i) likes statistics,
(ii) does not like it.
Refer to Q.2, Exercise 14.2. What is the empirical probability that an engineer lives: (i) less than 7 km from her place of work? (ii) more than or equal to 7 km from her place of work? (iii) within km from her place of work?