NCERT Class 9 Solutions: Statistics (Chapter 14) Exercise 14.2-Part 1

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Q-1 the Blood Groups of 30 Students of Class VIII Are Recoded as Follows:

A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O, A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O.

Represent this data in the form of a frequency distribution table. Which is the most common, and which is the rarest, blood group among these students?

Blood group of 30 students of Class VIII

Blood Group of 30 Students of Class VIII

Blood group of 30 students of Class VIII

From the above table the blood group AB is the lowest occurring and blood group O is the most common.

Q-2 The distance (in km) of 40 engineers from their residence to their place of work was 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

Construct a grouped frequency distribution table with class size 5 for the data given above taking the first interval as (5 not included). What main feature do you observe from this tabular representation?

Solution:

  • The grouped frequency distribution table of class size 5 has to be constructed.

  • The class intervals will be

  • From given the data, a grouped frequency distribution table can be constructed as below table.

    Grouped frequency distribution table of class size 5

    Grouped Frequency Distribution Table

    Grouped frequency distribution table of class size 5

  • The upper limit of a class is not included in the class

  • The class 0-5 of km, distance traveled by the engineer to their place of work

  • 5km is not included in this class

  • So, the next class , it is known as exclusive method.

  • It is 27 engineers out of 40 lives at a distance not more than 15km from their residence.

Q-3 The relative humidity (in %) of a certain city for a month of 30 days was as follows:

98.1 98.6 99.2 90.3 86.5 95.3 92.9 96.3 94.2 95.1 89.2 92.3 97.1 93.5 92.7 95.1

97.2 93.3 95.2 97.3 96.2 92.1 84.9 90.2 95.7 98.3 97.3 96.1 92.1 89

I. Construct a grouped frequency distribution table with classes 84 - 86, 86 – 88

II. Which month or season do you think this data is about?

III. What is the range of this data?

Solution (i)

  • The minimum and maximum relative humidity (in %) in the give raw data are 84.9 and 99.2 respectively.

  • It is given that 84-86 is one of the class intervals and class size is same.

So, the size is

So frequency distribution table is

Group frequency distribution table with classes 84-86, 86-88

Group Frequency Distribution of Relative Humidity

Group frequency distribution table with classes 84-86, 86-88

Solution (ii)

The data appears to be taken in the rainy season as the relatively high humidity

Solution (iii)

Range