Page No 283:
Question 2:
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 |
Page No 283:
Question 3:
In a particular section of Class IX, 40 students were asked about the months of their birth and the following graph was prepared for the data so obtained:
Find the probability that a student of the class was born in August.
Page No 283:
Question 4:
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 | 77 | 28 |
If the three coins are simultaneously tossed again, compute the probability of 2 heads coming up.
Page No 283:
Question 5:
An organization 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:
Suppose a family is chosen, find the probability that the family chosen is
(i) earning Rs 10000 − 13000 per month and owning exactly 2 vehicles.
(ii) earning Rs 16000 or more per month and owning exactly 1 vehicle.
(iii) earning less than Rs 7000 per month and does not own any vehicle.
(iv) earning Rs 13000 − 16000 per month and owning more than 2 vehicles.
(v) owning not more than 1 vehicle.
Page No 284:
Question 6:
A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows: 0 − 20, 20 − 30… 60 − 70, 70 − 100. Then she formed the following table:
Marks | Number of student |
0 − 20 20 − 30 30 − 40 40 − 50 50 − 60 60 − 70 70 − above | 7 10 10 20 20 15 8 |
Total | 90 |
Page No 284:
Question 8:
The distance (in km) of 40 engineers from their residence to their place of work were found as follows.
5 | 3 | 10 | 20 | 25 | 11 | 13 | 7 | 12 | 31 |
19 | 10 | 12 | 17 | 18 | 11 | 32 | 17 | 16 | 2 |
7 | 9 | 7 | 8 | 3 | 5 | 12 | 15 | 18 | 3 |
12 | 14 | 2 | 9 | 6 | 15 | 15 | 7 | 6 | 12 |
km from her place of work?Page No 285:
Question 11:
Eleven bags of wheat flour, each marked 5 kg, actually contained the following weights of flour (in kg):
4.97 5.05 5.08 5.03 5.00 5.06 5.08 4.98 5.04 5.07 5.00
Find the probability that any of these bags chosen at random contains more than 5 kg of flour.
