14. Statistics Class 9 Mathematics NCERT Exemplar Solutions (CBSE)
Chapter 14: Statistics – Class 9 Mathematics NCERT Exemplar Solutions (CBSE Board)
Chapter 14: Statistics
EXERCISE 14.1
Write the correct answer in each of the following :
1. The class mark of the class 90-120 is :
(A) 90 (B) 105 (C) 115 (D) 120
2. The range of the data :
25, 18, 20, 22, 16, 6, 17, 15, 12, 30, 32, 10, 19, 8, 11, 20 is
(A) 10 (B) 15 (C) 18 (D) 26
3. In a frequency distribution, the mid value of a class is 10 and the width of the class is 6. The lower limit of the class is :
(A) 6 (B) 7 (C) 8 (D) 12
4. The width of each of five continuous classes in a frequency distribution is 5 and the lower class-limit of the lowest class is 10. The upper class-limit of the highest class is:
(A) 15 (B) 25 (C) 35 (D) 40
5. Let m
be the mid-point and l
be the upper class limit of a class in a continuous frequency distribution. The lower class limit of the class is :
(A) 2m + l
(B) 2m – l
(C) m – l
(D) m – 2l
6. The class marks of a frequency distribution are given as follows :
15, 20, 25, ... .The class corresponding to the class mark 20 is :
(A) 12.5 – 17.5 (B) 17.5 – 22.5 (C) 18.5 – 21.5 (D) 19.5 – 20.5
7. In the class intervals 10-20, 20-30, the number 20 is included in :
(A) 10-20 (B) 20-30
(C) both the intervals (D) none of these intervals
8. A grouped frequency table with class intervals of equal sizes using 250-270 (270 not included in this interval) as one of the class interval is constructed for the following data :
268, 220, 368, 258, 242, 310, 272, 342, 310, 290, 300, 320, 319, 304, 402, 318,406, 292, 354, 278, 210, 240, 330, 316,406, 215, 258, 236. The frequency of the class 310-330 is:
(A) 4 (B) 5 (C) 6 (D) 7
9. A grouped frequency distribution table with classes of equal sizes using 63-72
(72 included) as one of the class is constructed for the following data :
30, 32, 45, 54, 74, 78, 108, 112, 66, 76, 88,40, 14, 20, 15, 35, 44, 66, 75, 84, 95, 96,102, 110, 88, 74, 112, 14, 34, 44. The number of classes in the distribution will be :
(A) 9 (B) 10 (C) 11 (D) 12
10. To draw a histogram to represent the following frequency distribution :
Class interval : 5-10 10-15 15-25 25-45 45-75
Frequency : 6 12 10 8 15
the adjusted frequency for the class 25-45 is :
(A) 6 (B) 5 (C) 3 (D) 2
11. The mean of five numbers is 30. If one number is excluded, their mean becomes 28. The excluded number is :
(A) 28 (B) 30 (C) 35 (D) 38
12. If the mean of the observations : x , x+3 , x+5 , x+7 , x+10
is 9, the mean of the last three observations is
(A) 1013
(B) 1023
(C) 1113
(D) 1123
13. If x
represents the mean of n
observations x1 , x2 , ………,xn
, then value of 
is:
(A) –1 (B) 0 (C) 1 (D) n – 1
14. If each observation of the data is increased by 5, then their mean
(A) remains the same (B) becomes 5 times the original mean
(C) is decreased by 5 (D) is increased by 5
15. Let x be the mean of x1 , x2 ,……,xn
and y
the mean of y1 , y2……, yn
. If z
is the mean of x1 , x2 ,……,xn , y1 , y2……, yn
, then z is equal to
(A) x+y
(B) x+y2
(C) x+yn
(D) x+y2n
16. If x is the mean of x1 , x2 ,……,xn , then for a≠0
, the mean of ax1 , ax2 ,……,axn , x1a , x2a , ……, xna
is
(A) a+1ax
(B) a+1ax2
(C) a+1axn
(D) a+1ax 2n
17. If x1 , x2 , ……… xn
are the means of n groups with n1 , n2 ,……,nn
number of observations respectively, then the mean x of all the groups taken together is given by :
(A) 
(B) 
(C) 
(D) 
18. The mean of 100 observations is 50. If one of the observations which was 50 is replaced by 150, the resulting mean will be :
(A) 50.5 (B) 51 (C) 51.5 (D) 52
19. There are 50 numbers. Each number is subtracted from 53 and the mean of the numbers so obtained is found to be –3.5. The mean of the given numbers is :
(A) 46.5 (B) 49.5 (C) 53.5 (D) 56.5
20. The mean of 25 observations is 36. Out of these observations if the mean of first 13 observations is 32 and that of the last 13 observations is 40, the 13 th observation is :
(A) 23 (B) 36 (C) 38 (D) 40
21. The median of the data : 78, 56, 22, 34, 45, 54, 39, 68, 54, 84 is
(A) 45 (B) 49.5 (C) 54 (D) 56
22. For drawing a frequency polygon of a continous frequency distribution, we plot the points whose ordinates are the frequencies of the respective classes and abcissae are respectively :
(A) upper limits of the classes (B) lower limits of the classes
(C) class marks of the classes (D) upper limits of perceeding classes
23. Median of the following numbers :
4, 4, 5, 7, 6, 7, 7, 12, 3 is
(A) 4 (B) 5 (C) 6 (D) 7
24. Mode of the data : 15, 14, 19, 20, 14, 15, 16, 14, 15, 18, 14, 19, 15, 17, 15 is
(A) 14 (B) 15 (C) 16 (D) 17
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