# NCERT Class 11-Math's: Exemplar Chapter –15 Statistics Part 12

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**Question 27:**

Following are the marks obtained by 9 students in a mathematics test:

The mean deviation from the median is:

(A)

(B)

(C)

(D)

**Answer: (C)**

**Question 28:**

The standard deviation of the data is

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 29:**

Let be *n* observations and be their arithmetic mean. The formula for the standard deviation is given by

(A)

(B)

(C)

(D)

**Answer: (C)**

**Question 30:**

The mean of observations is and their standard deviation is . The sum of all squares of all the observations is

(A)

(B)

(C)

(D)

**Answer: (C)**

**Question 31:**

Let be the observations with mean m and standard deviation s. The standard deviation of the observations is

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 32:**

Let be the observations with mean *m* and standard deviation *s*. The standard deviation of the observations is

(A)

(B)

(C)

(D)

**Answer: (C)**

**Question 33:**

Let be observations. Let for , where and are constants. If the mean of ’*s* is and their standard deviation is , the mean of is and standard deviation of ’*s* is , the values of and should be

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 34:**

Standard deviations for first natural numbers is

(A)

(B)

(C)

(D)

**Answer: (D)**

**Question 35:**

Consider the numbers . If is added to each number, the variance of the numbers so obtained is

(A)

(B)

(C)

(D)

**Answer: (D)**