NCERT Class 9 Solutions: Statistics (Chapter 14) Exercise 14.2-Part 3

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Q-7 The value of up to50 decimal places is given below:

3 1 4 1 5 9 2 6 5 3 5 8 9 7 9 3 2 3 8 4 6 2 6 4 3 3 8 3 2 7 9 5 0 2 8 8 4 1 9 7 1 6 9 3 9 9 3 7 5 10

I. Make a frequency distribution of the digits from 0 to 9 after the decimal point.

II. What are the most and the least frequently occurring digits?

Solution:

i) Frequency distribution table is given as:

Digits and their frequency in table

Digits and Their Frequency

ii) The most frequent digits are 3 and 9.

Q-8 Thirty children were asked about the number of hours they watched TV programmes in the previous week. The results were found as follows:

1 6 2 3 5 12 5 8 4 8 10 3 4 12 2 8 15 1 17 6 3 2 8 5 9 6 8 7 14 12

I. Make a grouped frequency distribution table for this data, taking class width 5 and one of the class intervals as.

II. How many children watched television for 15 or more hours a week?

Solution (i):

  • The minimum and maximum number of hours children watched TV programmes in the previous week it are 1 hour and 17 hours, respectively.

  • It is given than is one of the class intervals and class size is same.

  • The classes of equal size are , and

  • Frequency distribution table is as below:

Number of heads and their frequency

Frequency of Number of Heads

Solution (ii)

2 children watched television for 15 or more hours a week.

Q-9 A company manufactures car batteries of a particular type. The lives (in years) of 40 such batteries were recorded as follows:

2.6 3.0 3.7 3.2 2.2 4.1 3.5 4.5 3.5 2.3 3.2 3.4 3.8 3.2 4.6 3.7 2.5 4.4 3.4 3.3 2.9 3.0 4.3 2.8 3.5 3.2 3.9 3.2 3.2 3.1 3.7 3.4 4.6 3.8 3.2 2.6 3.5 4.2 2.9 3.6

Construct a grouped frequency distribution table for this data, using class intervals of size 0.5 starting from the intervals

Solution:

The number of years of car batteries is 2.2 years and 4.6 years.

It is given that class interval with uniform size of 0.5.

The class of equal size is

Frequency of life of batteries

Life of batteries (in years)

Frequency

Total