CBSE Class 8 Mathematics Data Handling Assignment Set 08

Question 1. The marks obtained by 40 students of class VIII in an examination are given below. Form a f.d.t taking one class interval as 10-15.
23, 2, 10, 20, 12, 09, 7, 0, 5, 3, 5, 16, 8, 5
12, 18, 8, 12, 6, 16, 17, 18, 3, 23, 7, 13, 18, 10
21, 13, 1, 07, 15, 13, 21, 24, 19, 16, 2, 23.
Answer: The frequency distribution table for the given marks is shown below:

In simple words: We sort the marks into groups of 5. For each group, we count how many students scored marks in that range.

Exam Tip: In continuous class intervals like 10-15, the upper limit 15 is not included in this group - it is counted in the next interval (15-20).

Question 2. The weights (in kg) of 35 persons are given below. Form a f.d.t. taking one class as 40-45 (45 not included)
48, 52, 55, 53, 42, 50, 58, 60, 53
55, 56, 58, 48, 63, 40, 56, 60, 55
53, 54, 62, 44, 50, 47, 40, 50, 48,
52, 62, 54, 47, 45, 51, 46, 43.
Answer: The frequency distribution table for the given weights is shown below:

In simple words: We place the weights into class groups of 5 kg each. We leave out the top value of each group and count it in the next one.

Exam Tip: Always sum up the frequency column at the end to make sure the total matches the total number of people given in the question.

Question 3. Monthly pocket expenses of 30 students of a class are given below. Construct a f.d.t. by taking one class interval as 25-35 (35 not included)
58, 45, 40, 38, 73, 35, 38, 72, 65, 54,
80, 77, 39, 38, 40, 59, 27, 71, 38, 50,
76, 60, 57, 83, 62, 80, 40, 42, 84, 44.
Answer: The frequency distribution table for the monthly pocket expenses is shown below:

In simple words: Each group covers Rs. 10 of expense. We count how many students spend an amount in each group.

Exam Tip: When a number lies exactly on the boundary, like 35 or 45, always place it into the higher class interval.

Question 4. Following is the f.d.t of 25 persons working in an office and answer the following questions.

(a) What is the class size?
(b) What is the lower limit of class 30-40?
(c) What is the upper limit of class 50-60?
(d) What is the class mark of class 20-30?
(e) What is the frequency of class 40-50?
Answer:
(a) Class size = Upper limit - Lower limit = \( 30 - 20 = 10 \)
(b) The lower limit of the class 30-40 is 30.
(c) The upper limit of the class 50-60 is 60.
(d) Class mark = \( \frac{\text{Lower limit} + \text{Upper limit}}{2} = \frac{20 + 30}{2} = \frac{50}{2} = 25 \)
(e) The frequency of the class 40-50 is 6.
In simple words: Class size is the width of a group. Class mark is the midpoint of a group. Lower and upper limits are the boundary numbers of each class.

Exam Tip: Remember that class size is found by subtraction (Upper limit - Lower limit), while class mark is found by taking their average.

Question 5. A group of students spent the following minutes in doing their home-work. Prepare a f.d.t by choosing your own class interval
50, 80, 90, 65, 40, 10, 50, 5, 90, 30, 35,
45, 75, 5, 85, 95, 60, 35, 75, 25, 75, 30,
75, 45, 45, 75, 20, 65, 15, 35, 35, 25, 45.
Answer: The minimum time is 5 minutes and the maximum time is 95 minutes. Taking class intervals of size 10, the frequency distribution table is given below:

In simple words: We make groups of 10 minutes from 0 to 100. Then we count how many students spent time in each range.

Exam Tip: When choosing class intervals yourself, pick convenient multiples of 5 or 10 that comfortably cover both the minimum and maximum data values.