NCERT Class 11-Math's: Exemplar Chapter –15 Statistics Part 3
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Question 6:
Life of bulbs produced by two factories A and B are given below:
Length of life (in hours) | Factory A (Number of bulbs) | Factory B (Number of bulbs) |
The bulbs of which factory are more consistent from the point of view of length of life?
Answer:
Here , let A (assumed mean) .
Length of life (in hours) | Mid values | Factory A | Factory B | |
For factory A
Mean
Therefore, Coefficient of variation
For factory B
Mean
Therefore, Coefficient of variation
Since . of factory . of factory Factory B has more variability which means bulbs of factory A are more consistent.
Objective Type Questions
Choose the Correct Answer Out of the Four Options Given Against Each of the Examples 7 to 9 (M.C.Q.)
Question 7:
The mean deviation of the data from the mean is
(A)
(B)
(C)
(D)
Answer:
(B) Is the correct answer
Question 8:
Variance of the data is . Then variance of will be
(A)
(B)
(C)
(D)
Answer:
(C) Is the correct answer.
When each observation is multiplied by , then variance is also multiplied by .
Question 9:
A set of values has standard deviation . The standard deviation of n values will be
(A)
(B)
(C)
(D)
Answer:
(A) Is correct answer.
If each observation is increased by a constant , then standard deviation is unchanged.
15.3 EXERCISE
Short Answer Type
Question 1:
Find the mean deviation about the mean of the distribution:
Size | |||||
Frequency |
Answer: