NCERT Solutions for class 11 Maths | Chapter 15 - Statistics

Questions
1 What should be the modal class

Class 11 Chapter 15 statistics

A 10-20
B 30-40
C 40-50
D 50-60

Answer:30-40
2 The abscissa of the point of interaction of the ‘less than type’ and of the ‘more than type’ cumulative frequency curve of grouped data gives
A mode
B median
C mean
D all of the above

Answer:median
3 Construction of a cumulative frequency table is useful determining the
A mean
B mode
C medien
D all of the above

Answer:medien
4 The mean deviation of the data 3, 10, 10, 4, 7, 10, 5 from the mean is
A 2
B 2.57
C 3
D 3.57

Answer:2.57
5 The mean of 100 observations is 50 and their standard deviation is 5. The sum of all squares of all the observations is
A 50,000
B 250,000
C 252500
D 255000

Answer:252500
6 Consider the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. If 1 is added to each number, the variance of the numbers so obtained is
A 6.5
B 2.87
C 3.87
D 8.25

Answer:8.25
7 Consider the first 10 positive integers. If we multiply each number by −1 and then add 1 to each number, the variance of the numbers so obtained is
A 8.25
B 6.5
C 3.87
D 2.87

Answer:8.25
8 The standard deviation of first 10 natural numbers is
A 5.5
B 3.87
C 2.97
D 2.87

Answer:2.87
9 If the S.D. of a set of observations is 8 and if each observation is divided by −2, the S.D. of the new set of observations will be
A −4
B −8
C 8
D 4

Answer:4
10 Let x1, x2 , ...,xn be values taken by a variable X and y1, y2, ..., yn be the values taken by a variable Y such that yi= axi+ b, i = 1, 2,..., n. Then,
A Var (Y) = a2 Var (X)
B Var (X) = a2 Var (Y)
C Var (X) = Var (X) + b
D none of these

Answer:Var (Y) = a2 Var (X)
11 The sum of the squares deviations for 10 observations taken from their mean 50 is 250. The coefficient of variation is
A 10 %
B 40 %
C 50 %
D none of these

Answer:10 %
12 The mean deviation of the numbers 3, 4, 5, 6, 7 from the mean is
A 25
B 5
C 1.2
D 0

Answer:1.2
13 A batsman scores runs in 10 innings as 38, 70, 48, 34, 42, 55, 63, 46, 54 and 44. The mean deviation about mean is
A 8.6
B 6.4
C 10.6
D None of these

Answer:None of these
14 The mean deviation from the median is
A equal to that measured from another value
B maximum if all observations are positive
C greater than that measured from any other value.
D less than that measured from any other value.

Answer:less than that measured from any other value.
15 The mean deviation of the data 2, 9, 9, 3, 6, 9, 4 from the mean is
A 2.23
B 2.57
C 3.23
D 3.57

Answer:2.57
16 Mean deviation for n observations x1 , x2 , ..........., xn from their mean x is given by
A ∑(xi - x) where (1 ≤ i ≤ n)
B {∑|xi - x|}/n where (1 ≤ i ≤ n)
C ∑(xi - x)2 where (1 ≤ i ≤ n)
D {∑(xi - x)2 }/n where (1 ≤ i ≤ n)

Answer:{∑|xi - x|}/n where (1 ≤ i ≤ n)
17 One of the methods of determining mode is
A Mode = 2 Median - 3 Mean
B Mode = 2 Median + 3 Mean
C Mode = 3 Median - 2 Mean
D Mode = 3 Median + 2 Mean

Answer:Mode = 3 Median - 2 Mean
18 If the mean of the following data is 20.6, then the value of p is

x: 10 15 p 25 35

f: 3 10 25 7 5

A 30
B 20
C 25
D 10

Answer:20
19 In a symmetric distribution
A Mean ≠ Median = Mode
B Mean = Median ≠ Mode
C Mean ≠ Median ≠ Mode
D Mean = Median = Mode

Answer:Mean = Median = Mode
20 The algebraic sum of the deviation of 20 observations measured from 30 is 2. So, the mean of observations is
A 30.0
B 30.1
C 30.2
D 30.3

Answer:30.1

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