Stats Practice material

1. Page 1 of 4
Faculty: AMIR KHATRI
1. Dispersion
a. summarize the data into a single value.
b. measures the concentration of a set of observations.
c. Measures the scatterness of a set of observations.
d. None of these
2. Which measure of dispersion is based on all observations?
a. range b. quartile deviation
c. mean deviation d. all of these
3. which measure of dispersion is not affected by extreme observations?
a. range b. quartile deviation
c. mean deviation d. all of these
4. The appropriate measure of dispersion for open end classification is:
a. range b. quartile deviation
c. mean deviation d. all of these
5. which of the following is a positional measure?
a. M.D b. Q.D c. S.D d. C.V
6. Which measure of dispersion is based on the absolute deviations only?
a. M.D b. Q.D c. S.D d. Range
7. Mean deviation from ‘A’ is minimum if A =
a. mean b. mode
c. median d. none of these
8. If the marks scored by all 10 students are the same as 45, the standard deviation of
marks for the 10 students is
a. 45 b. 0
c. 10 d. none of these
9. When the variability of two series is to be compared, which of the following should be
used?
a. absolute measure of average b. absolute measure of dispersion
c. relative measure of dispersion d. relative measure of average
10. For two numbers S.D is always
a. half the range b. double the range
c. square the range d. equal to range
11. Which of the following measure is independent of unit of measurement?
a. S.D b. coefficient of variation
c. range d. Q.D

2. Page 2 of 4
Faculty: AMIR KHATRI
12. If each & every observations are decreased by 2 then M.D of new observation
a. decreases by 2 b. remains same
c. increases by 2 d. none of these
13. If all the observations are multipliedby 3,
a. C.V is also three times the previous C.V
b. S.D remains unchanged
c. C.V remains unchanged
d. none of these
14. If x &y are related by y = 3x + 4 & M.D from median & median of x is 3 & 16 respectively,
then find the coefficient of M.D from median for y is
a. 0.19 b. 0.25 c. 0.058 d. 0.17
15. The variance of a set of data is 9. If every item is doubled then what will be the variance
of the resulting data set?
a. 9 b. 36 c. 18 d. 4.5
16. The coefficient of mean deviation of first five natural numbers is
a. 0.3 b. 0.4 c. 0.5 d. 0.7
17. Which empirical relation is correct for symmetric distribution?
a. M.D =
3
4
S.D b. M.D =
4
5
S.D
c. M.D =
4
3
S.D d. M.D =
5
4
S.D
18. Q.D is …….. of S.D in a symmetric distribution.
a. 1/3 b. 2/3 c. 1/4 d. ¾
19. The following information is available on two group I & II. Find combined standard
deviation.
Group I n1 = 10, 𝑥̅1 = 28, S1
= 35
Group II n2 = 20, 𝑥̅2 = 24, S2
= 35
a. 1228.50 b. 35.50 c. 1822.05 d. 35.05
20. Sum of 20 observations is 420 & the sum of the positive deviations taken from mean is
180. Then find coefficient of deviation
a.
3
7
b.
60
7
c. 9 d. 21
21. ∑( 𝑥 − 20) = 0, ∑( 𝑥 − 20)2 = 400𝑛. Find C.V
a. 0 b. 100 c. 20 d. 2000

3. Page 3 of 4
Faculty: AMIR KHATRI
22. Mean & S.D of 10 observations are 80 & 4 respectively. Find the sum of squares of
observations.
a. 64160 b. 680 c. 46.4 d. none of
these
23. Find mean deviation from median for 5, 5, 5, 5, 5, 5.
a. 0 b. 5 c. 1 d. none of these
24. The M.D of 1, 2, 3, 4, 5, 6, 7, hence M.D of 2.7, 4.7, 6.7, 8.7, 10.7, 12.7, 14.7 is
a. 3.42 b. 1.78 c. 3.49 d. none of
these
25. A shift of scale has no impact on
a. Range b. Q.D c. S.D d. C.V
26. If every item in a series is increased by the same quantity, the quartile deviation
a. increases by the same quantity
b. decreases by the same quantity
c. remain same
d. increases by the square of that quantity
27. If the S.D of x is 3.5, what is the variance of (10 – 2x)?
a. 49 b. 3 c. -14.5 d. 51
28. If all the observations in a data is increased by the same quantity then which of the
following is true?
a. range decreasesby same quantity
b. standard deviation remains unchanged
c. coefficient of variations increases
d. both (b) & (c)
29. If x & y are related by 2y = 3x +10, then
a. 2Ry = Rx b. 2Ry = 3Rx + 10
c. 2Ry = 3Rx d. Ry = 3Rx
30. If each observation of a raw data whose variance is k is multiplied by m, then variance
of the new set is:
a. k2
m2
b. km2
c. km d. √ 𝑘 𝑚
31. The quartile deviation of a variable y is Q. the quartile deviation of the variable
𝑎1 𝑦+ 𝑎2
𝑎3
is
a. |
𝑎1
𝑎3
|Q b. | 𝑎1|Q
c.
𝑎1 𝑄+ 𝑎2
𝑎3
d. none of these
32. If 2 C.V = 7 𝑥̅ & 2S.D = 7 𝑥̅. Find 𝑥̅.
a. 100 b. 1 c. 3.5 d. none of
these

4. Page 4 of 4
Faculty: AMIR KHATRI
33. Mean & variance of 10 observations are 15 & 4. If one observation was taken as 12
instead of 21. Find correct 𝑥̅ & S.D.
a. 15, 4.23 b. 15.9, 4
c. 15.9, 4.23 d. none of these
34. For the data given below obtain combined S.D.
A
𝑥̅ = 35, ∑ 𝑥 = 875,
S1 = 1
B
n = 25, 𝑥̅ = 45, ∑ 𝑥2
= 50725
a. 2.45 b. 5.24 c. 5.42 d. 4.25
35. Sum & difference between the two extreme qaurtiles is 298 & 18 respectively. Compute
coefficient of quartile deviation.
a. 0.06 b. 16.56 c. 9 d. 149
36. The deviation taken from mean are -12, -6, 0, 8, 10. Calculate mean deviation from
mean.
a. 68.8 b. 0 c. 7.2 d. 8.29
37. Quartile deviation of 1, 2, 3, 4, 5, 6, 7 is 2 hence find the quartile deviation of 6.6, 9.6,
12.6, 15.6, 18.6, 21.6, 24.6.
a. 6 b. 3.2 c. 7.2 d. 9.6
38. For a data having two observations, standard deviation is 4. Then range is
a. 8 b. 2 c. 1 d. none of these
39. For two data sets, number of obsewrvations & means are equal to 50. If combined
standard deviation is 5 then whichj of the following is true?
a. S1 + S2 = 5 b. S1 + S2 = 50
c. 𝑆1
2
+ 𝑆2
2
= 50 d. 𝑆1
2
+ 𝑆2
2
= 5
40. If sum, sum of deviations & sum of squares of deviations from mean for 10 observations
is 590, 216 & 6488 respectively, then coeffucient of mean deviation is
a. 0.37 b. 11 c. 3 d. 21.6