Average and Standard Deviation : Mathematics Objective Questions
1. The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 51.4 years. The ratio of number of boys to the numbers of girls in the class is
a) 1 : 2 b) 3 : 4 c) 3 :5 d) 2 : 3
2. The mean weight of 9 items produced by a factory was 5 kg. By the production of one more item, the mean weight became 5.5 kg. Then the weight of the item produced is
a) 8 kg b) 10 kg c) 12 kg d) 14 kg
3. The densities of three liquids are D, 2D and 3D. What will be the density of the resulting mixture, if equal volumes of the three liquids are mixed?
a) 6 D b) 1.4 D c) 2 D d) 3 D
4. Average mark scored by a class of 31 students is 40. If one student is left out, the average falls to 39. Mark of this child is
a) 60 b) 41 c) 70 d) 39
5. The average age of 4 sisters is 7 years. If the age of mother is included, the average is increased by 6 years. The age of the mother is
a) 28 years b) 33 years c) 34 years d) 37 years
6. In which of the following, the average is 100?
a) 100,105,110,112,120 b) 94,95,96,97,100
c) 94, 99,100,101,106 d) None of these
7. The marks obtained by 11 students in Computer Science are as follows: 94,94,91,89,87,92,97,88,90,98,92.
How many of the about values are below the average ?
a)
8. The mean and median of a certain value are 2.5 and 3 respectively. Then the mode of the variate is
a) 2 b) 3 c) 3.5 d) none of these
9. On 5 days, the price of gold was Rs. 380 on each day. On the next 10 days, the price was Rs. 390 on each day. What was the daily average price ?
a) Rs. 385.00 b) Rs. 386.00 c) Rs. 390.00 d) None of these
10. Which tow series of the following three series have the same mode ?
1) 5 8 8 13 9 12 8
2) 8 12 6 8 10 8 7
3) 9 8 14 9 12 9 8
a) series 1 and series 2 b) series 1 and series 3 c) series 2 and series 3 d) none of these
11. The heights of eight six ? year old boys are given below :
Height ( in cm ) : 80, 81, 83, 81, 78, 80, 79, 81 . The mode is
a) 81 b) 79 c) 73 d) 76
12. Daily average rainfall in a week is 7 cms, daily average rainfall in the first 6 days of the week is 6cms. What is the rainfall on the last day?
a) 1cm b) 7 cms c) 13 cms d) 43 cms
13. Five years ago, the average age of A, B, C and D was 45 years. With E joining them now, the average age of all the five is 49 years. The age of E in years is
a) 25 b) 40 c) 45 d) 49
14. The most stable measure of Central Tendency is
a) The mean b) The median c) The mode d) none of these
15. Secondary data should be used them because
a) it is easily available b) it is less costly to use
c) the source and purposes known d) the data meets the purpose
16. A Library has an average number of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with as Sunday is
a) 285 b) 276 c) 250 d) 280
17. The empirical relationship connecting the three main averages is
a) Mean ? Median = Mean ? Mode
b) Mode ? Median = 2(Median ? Mean)
c) Mean ? Mode = 3(Mean ?Median )
d) 3 ( Mean ? Mode ) = Median ? Mode
18. In a normal distribution, which relation is true?
a) mean ? median = mode b) mean ? median ? mode
c) mean = median ? mode d) mean = median = mode
19. The average that can be found out with help of Ogives is
a) Mean b) Median c) Range d) Harmonic mean
20. The average income of sample A is 300 and the average income of sample B is 200. Their sizes are 10 and 15 respectively. Find the combined average.
a) 240 b) 20 c) 230 d) None of these
21. A student has to score 40% marks to pass. He gets 178 marks and fails by 22 marks. The maximum mark is
a) 200 b) 500 c) 800 d) 1000
22. The mode of the numbers 6,5,5,4,5,5,4,4,6 is
a) 4 b) 5 c) 6 d) None of these
22. The less reliable measure of dispersion is
a) Regression coefficient b) Standard deviation
c) Correlation coefficient d) Range
23. The average of first five odd natural numbers
a) 3.0 b) 4.5 c) 5.0 d) 6.0
24. A cricketer makes 72, 59,18,101 and 7 runs respectively in five matches played by him. Find his average score.
a) 50.0 b) 51.0 c) 51.4 d) none of these
25. In a class of 40 students 5 were absent for a test. The average marks in it came out of 60. Those 5 students wrote a retest and the average marks calculated for all the 40 students came out as 60. The total marks scored by those 5 students were
a) 0 b) 100 c) 300 d) None of these
26. The average age of a family of 6 members is 25 years. The average age of the family after a 45 year old member leaves is
a) 20 years b) 21 years c) 22 years d) 23 years
27. The average weight of a class of 40 students is 50 kg. if the teacher is also included, the average weight increases to 50.5 kg. the weight of the teacher is
a) 70.5 kg b) 71.5 kg c) 72.5 kg d) 75 kg
28. The mean of 100 observations is 60. What will be the new value of mean, if 8 is subtracted from each observation and then divided by 4 ?
a) 50 b) 52 c) 13 d) 14
29. The most stable measure of central tendency is
a) the mean b) the median c) the mode d) geometric mean
30. The heights of 5 persons are 59, 63, 68, 60,72 inches. The value of range is
a) 10 b) 13 c) 12 d) 15
31. The sum of deviations taken from arithmetic mean is
a) 2 b) 0 c) 4 d) 5
32. The arithmetic mean of 21, 30, 33 and 64 is
a) 35 b) 28 c) 37 d) 42
33. In a symmetrical distribution
a) mean > median> mode b) mean < median> mode
c) mean = median = mode d) mean > median< mode
34. What is the median of 45, 65, 35, 42, 75, 21, 64, 5 ?
a) 48.5 b) 47.6 c) 42 d) None of these
35. The prices of commodity in six days are Rs.200, Rs.210, Rs.208, Rs.160, Rs.220, Rs.250. The range is
a) Rs.208 b) Rs.210 c) Rs.160 d) Rs.90
36. If the average marks of 20 male and 30 female students in a class are respectively 45 and 40, the average marks of the class is
a) 41 b) 42 c) 44 d) 42.5
37. In a symmetrical distribution with median equal to 10, the mean is
a) greater than 10 b) less than 10 c) equal to 10 d) not equal to 10
38. The average, which gives equal importance?s to all times in the distribution, is
a) median b) mode c) both a & b d) neither a nor b
39. For unimodal distribution, which one of the following diagrams is used to find the mode ?
a) Pie ? diagram b)Frequency polygon c) Ogive d) None
40. With the help of Ogive curve, one can determine
a) median b) decibels c) percentiles d) all these
41. The median of the first 42 natural number is
a) 21 b) 21.25 c) 21.5 d) 22
42. Average marks of 30 boys of a class is 70. Average marks of 20 girls of the class is 80. what is the average marks per students class ?
a) 70 b) 74 c) 75 d) 80
43. The mean and mode of the following set of values are 66,65,61,65,66,60,65
a) 62 and 63 b) 63 and 64 c) 64 and 65 d) 62 and 65
44. If the mean farm ? size is 5 acres, find the value of y.
Farm ? size in acres : 1 2 3 y
Frequency : 10 20 30 40
a) 4 b) 9 c) 10 d) None of these
45. The mode of the following data is
2, 3, 5, 3, 7, 3, 5, 2, 7, 3
a) 5 b) 2 c) 3 d) 7
46. The prices of a share during the seven days in a week are as follows:
Price (in Rs.): 102, 96, 98, 101, 104, 103, 100
The median value is:
a) 104 b) 102 c) 101 d) 100
47. The range of given in value id
a) x standard deviation b) Maximum value – Minimum value
c) Standard Deviation/Mean d) None of these
48. Variance is
a) Always negative b) May be positive or negative
c) Always positive d) None of these
49. The standard deviation of series 1,2, 3, 4, 5 is
a) b) c) 11 d) 55
50. A class contains 10 students. The marks obtained by them in a test are 43, 48, 65, 57, 31, 60, 37, 48, 78, 59.
a) 3 b) 4 c) 5 d) 7
51. The median of the first 21 number is
a) 10 b) 11 c) 12 d) None of these
52. The average marks of 8 students was found to be 80. How ever, it was later found that the value 90 was wrongly copied as 32. What is correctly average?
a) 82 b) 81 c) 80 d) 79
53. Which of the following sets of data has equal median and mode?
a) 1, 5, 7, 7, 8, 10 b) 1, 3, 5, 7, 9, 5 c) 2, 4, 6, 8, 10, 8 d) 1, 2, 3, 7, 8, 8, 10
54. For a more than Ogive, which of the following statements are false:
I) As X decreases Y also decreases II) As X increases Y decreases
III) As X decreases Y increases IV) As X increases Y also increases
Of these:
a) I and II are incorrect b) II and III are incorrect c) III, IV are incorrect d) I and IV are incorrect
55. Consider the following set of values: 31,27,30,28,29,23
What can you say about the mean median and mode of these values?
a) They are same b) They are different c) Cannot say surely d) None of these
56. The average age of 30childrens in a class is 9 years. If the teacher?s age is added, the average age become 10 years, then teacher?s age in years in
a) 40 b) 31 c) 30 d) 27
57. The average age of a husband and wife who were married four years ago was 30 ,then the average age of the family consisting of the husband wife and a child now is 23. The age of the child is
a) Less than 1 year b) 3 years c) 2 years d) 1 year
