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:

Life of Bulbs Produced by Two Factories
Life of Bulbs Produced by Two Factories

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) .

Life of Bulbs Produced by Two Factories
Life of Bulbs Produced by Two Factories

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:

Find the Deviation
Find the Deviation

Size

Frequency

Answer:

Developed by: