NCERT Mathematics Class 9 Exemplar Ch 14 Statistics and Probability Part 6
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Exercise 14.2
Q.1. The frequency distribution:
Marks | ||||
Number of Students |
Has been represented graphically as follows:
Do you think this representation is correct? Why?
Answer: Not correct. The classes are of varying widths, not of uniform widths.
Q.2. In a diagnostic test in mathematics given to students, the following marks (out of 100) is recorded:
which ‘average’ will be a good representative of the above data and why?
Answer: Median will be a good representative of the data, because
(i) Each value occurs once,
(ii) The data is influenced by extreme values.
Q.3. A child says that the median of is. What doesn’t the child understand about finding the median?
Answer: Data has to be arranged in ascending (or descending) order before finding the median.
Q.4. A football player scored the following number of goals in the 10 matches:
1, 3, 2, 5, 8, 6, 1, 4, 7, 9 since the number of matches is 10 (an even number), therefore, the median
=
=
Is it the correct answer and why?
Answer: No, the data have first to be arranged in ascending (or descending) order before finding the median.
Q.5. Is it correct to say that in a histogram, the area of each rectangle is proportional to the class size of the corresponding class interval? If not, correct the statement.
Answer: It is not correct. In a histogram, the area of each rectangle is proportional to the frequency of its class.
Q.6. The class marks of a continuous distribution are: and Is it correct to say that the last interval will be? Justify your answer.
Answer: It is not correct. Reason is that difference between two consecutive marks should be equal to the class size.