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NCERT Solutions for class 11 Maths | Chapter 15 - Statistics

(1) If one of the observation is zero then geometric mean is
[A] (Sum of observation)/n
[B] (Multiplication of all observations)n
[C] (Multiplication of all observations)1/n
[D] 0
Answer: 0
(2) If the varience of the data is 121 then the standard deviation of the data is
[A] 121
[B] 11
[C] 12
[D] 21
Answer: 11

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(3) The median and SD of a distributed are 20 and 4 respectively. If each item is increased by 2, the new median and SD are
[A] 20, 4
[B] 22, 6
[C] 22, 4
[D] 20, 6
Answer: 22, 4
(4) The mean of a group of 100 observations was found to be 20. Later on, it was found that three observations were incorrect, which was recorded as 21, 21 and 18. Then the mean if the incorrect observations are omitted is
[A] 18
[B] 20
[C] 22
[D] 24
Answer: 20
(5) If the mean of first n natural numbers is 5n/9, then n =
[A] 5
[B] 4
[C] 9
[D] 10
Answer: 9
(6) If r is the correlation coefficient, then
[A] |r| ≤ 1
[B] r ≤ 1
[C] |r| ≥ 1
[D] r ≥ 1
Answer: |r| ≤ 1
(7) If a variable takes discrete values x + 4, x – 7/2, x – 5/2, x – 3, x – 2, x + 1/2, x – 1/2, x + 5 (x > 0), then the median is
[A] x – 5/4
[B] x – 1/2
[C] x – 2
[D] x + 5/4
Answer: x – 5/4
(8) Range of the data 4, 7, 8, 9, 10, 12, 13 and 17 is
[A] 4
[B] 17
[C] 13
[D] 21
Answer: 13
(9) When tested the lives (in hours) of 5 bulbs were noted as follows: 1357, 1090, 1666, 1494, 1623. The mean of the lives of 5 bulbs is
[A] 1445
[B] 1446
[C] 1447
[D] 1448
Answer: 1446
(10) Which one is measure of dispersion method
[A] Renge
[B] Quartile deviation
[C] Mean deviation
[D] all of the above
Answer: all of the above
(11) The coefficient of variation is computed by
[A] S.D/.Mean×100
[B] S.D./Mean
[C] Mean./S.D×100
[D] Mean/S.D.
Answer: S.D./Mean
(12) If the difference of mode and median of a data is 24, then the difference of median and mean is
[A] 12
[B] 24
[C] 8
[D] 36
Answer: 12
(13) If covariance between two variables is 0, then the correlation coefficient between them is
[A] nothing can be said
[B] 0
[C] positive
[D] negative
Answer: 0
(14) If Mean = Median = Mode, then it is
[A] Symmetric distribution
[B] Asymmetric distribution
[C] Both symmetric and asymmetric distribution
[D] None of these
Answer: Symmetric distribution
(15) Varience is independent of change of
[A] origin only
[B] scale only
[C] origin and scale both
[D] None of these
Answer: origin only
(16) Let x1, x2, x3, ……… , xn, be n observations and X be the arithmetic mean. Then formula for the standard deviation is given by
[A] ∑(xi – mean)²
[B] ∑(xi – mean)2 /n
[C] √{∑(xi – mean)²/n}
[D] None of these
Answer: √{∑(xi – mean)²/n}
(17) The sum of 10 items is 12 and the sum of their squares is 18. The standard deviation is
[A] 1/5
[B] 2/5
[C] 3/5
[D] 4/5
Answer: 3/5
(18) 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
(19) If mode of a series exceeds its mean by 12, then mode exceeds the median by
[A] 4
[B] 8
[C] 6
[D] 12
Answer: 8
(20) 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

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