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Chapter 14 : Statistics
Q. In a retail market, fruit vendors were selling mangoes kept in packing boxes. These boxes contained varying number of mangoes. The following was the distribution of mangoes according to the number of boxes.
No. of mangoes
5052
5355
5658
5961
6264
No. of boxes
15
110
135
115
25
If mean number of mangoes kept in a pocket box. Which method of finding the mean did you choose?
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Q. The following distribution shows the daily pocket allowance of children of a locality, The mean pocket allowance is Rs.18. Find the missing frequency f.
Daily pocket Allowance (in Rs.)
Number of children
11-13
7
13-15
6
15-17
9
17-19
13
19-21
f
21-23
5
23-25
4

  1. f=10
  2. f=20
  3. f=15
  4. f=19
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Q. To find out the concentration of SO2 in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:
Concentration of SO2 (in ppm)
Frequency
0.000.04
4
0.040.08
9
0.080.12
9
0.120.16
2
0.160.20
4
0.200.24
2
Find the mean concentration of SO2 in the air.
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Q. The table below shows the daily expenditure on food of 25 households in a locality.
Daily expenditure (in Rs.)100-150150-200200-250250-300300-350
Number of households:451222
Find the mean daily expenditure on food by a suitable method.
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Q. Consider the following distribution of daily wages of 50 workers of a factory:
Find the mean daily wages of the workers of the factory by using appropriate method.
Daily wages(in rs)Number of workers
500-20012
520-54014
540-5608
560-5806
580-60010
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Q. The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.
Literacy rate (in %)
4555
5565
6575
7585
8595
No. of cities
3
10
11
8
3
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Q. A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.
Number of days0661010141420202828383840
Number of students111074431
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Q. Thirty women were examined in a hospital by a doctor and the number of heart beats per minute were recorded and summarized as follows. Find the mean heart beats per minute for these women, choosing a suitable method.
Number of heart beats
per minute
6568687171747477778080838386
Number of women2438742
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Q. A survey was conducted by a group of students as a part of their environment awareness programme, in which they collected the following data regarding the number of plants in 20 houses in a locality.Find the mean number of plants per house.

Number of plants
02
24
46
68
810
1012
1214
Number of houses
1
2
1
5
6
2
3

Which method did you use for finding the mean, and why?
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Q. A student noted the number of cars passing through a spot on a road for 100 periods each of 3 minutes and summarised it in the table given below. Find the mode of the data:
Number of cars
010
1020
2030
3040
4050
5060
6070
7080
Frequency
7
14
13
12
20
11
15
8
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Q. The following table shows the ages of the patients admitted in a hospital during a year.
Age (in years)
No. of patients
5-15
6
15-25
11
25-35
21
35-45
23
45-55
14
55-65
5
Find the mode and the mean of the data given above. Compare and interpret the measures of central tendency.
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Q. The following distribution gives the state-wise teacher-student ratio in higher secondary schools of India. Find the mode and mean of this data. Interpret the two measures.
Number of students per teacher
Number of states/U.T.
1520
3
2025
8
2530
9
3035
10
3540
3
4045
0
4550
0
5055
2
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Q. The given distribution shows the number of runs scored by some top batsmen of the world in one-day international cricket matches.
Runs scored
Number of batsmen
30004000
4
40005000
18
50006000
9
60007000
7
70008000
6
80009000
3
900010000
1
1000011000
1
Find the mode of the data.
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Q. The following data gives the distribution of total monthly household expenditure of 200 families of a village. Find the modal monthly expenditure of the families. Also, find the mean monthly expenditure:
Expenditure (in C)
Number of families
10001500
24
15002000
40
20002500
33
25003000
28
30003500
30
35004000
22
40004500
16
45005000
7
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Q. The following data gives the information on the observed lifetimes (in hours) of 225 electrical components:
Lifetimes (in hours)
020
2040
4060
6080
80100
100120
Frequency
10
35
52
61
38
29
Determine the modal lifetimes of the components.
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Q. If the median of the distribution given below is 28.5, find the values of x and y.
Class interval
Frequency
010
1020
2030
3040
4050
5060
5
x
20
15
y
5
Total
60
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Q. The following table gives the distribution of the life time of 400 neon lamps:
Life time (in hours)
Number of lamps
15002000
20002500
25003000
30003500
35004000
40004500
45005000
14
56
60
86
74
62
48
Find the median life time of a lamp.
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Q.

The distribution below gives the weights of 30 students of a class. Find the median weight of the students.

Weight(in Kgs)4045455050555560606565707075Number of students2386632

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Q. The lengths of 40 leaves of a plant are measured correct to the nearest millimetre, and the data obtained is represented in the following table:
Length (in mm)
Number of leaves
118126
127135
136144
145153
154162
163171
172180
3
5
9
12
5
4
2
Find the median length of the leaves.
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Q. A life insurance agent found the following data for distribution of ages of 100 policy holders. Calculate the median age, if policies are only given to person having age 18 years onwards but less than 60 years.
Age (in years)
No. of policy holders
Below 20
2
Below 25
6
Below 30
24
Below 35
45
Below 40
78
Below 45
89
Below 50
92
Below 55
98
Below 60
100

  1. 62.12 years
  2. 53.53 years
  3. None of these
  4. 35.76 years
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