*** Find the MEAN of following:
1)
A) 7, 9, 4, 6, 5. 6.2
B) Value Frequency
1 7
2 11
3 16
4 17
5 26
6 31
7 11
8 1
9 1
10 1 4.59
C) Class Frequency
0 - 10 4
10 - 20 7
20 - 30 8
30 - 40 4
40 - 50 2 22.2
D) Height in c.m Frequency
130 - 134 5
135 - 139 15
140 - 144 28
145 - 149 24
150 - 154 17
155 - 159 10
160 - 164 1 145.35
E) Class Frequency
0 - 4 2
5 - 14 8
15 - 19 6
20 - 34 14
35 - 39 5 21.29
F) weekly wages(₹) No.of workers
Below 10 8
Below 20 18
Below 30 45
Below 40 90
Below 50 113
Below 60 120 32.17
G) Marks No. of students
More than 0 60
More than 10 56
More than 20 40
More than 30 20
More than 40 10
More than 50 3 26.5
H) Value No. of boys
Under ₹10 245
₹10 Under ₹20 383
₹20 Under ₹30 205
₹30 Under ₹40 89
₹40 Under ₹50 47
₹50 Under ₹60 21
₹60 Under ₹70 10
Find a) the total turnover b) the mean value of a single order. ₹19130, ₹19.13, ₹16.67
I) The mean of the following is 20.5. find the missing frequency.
X: 10 15 20 25 30
F: 5 7 -- 12 6 40
J) The mean of the following frequency table is 50. But the frequency a and b in classes 20-40 and 60-80 are missing. Find the missing frequencies.
Class Frequency
0 - 20 19
20 - 40 a
40 - 60 32
60 - 80 b
80 - 100 19 28, 24
K) The A. M calculated from the following frequency distribution is known to be 67.45 inches. Find the value of a.
Height (inches) frequency
60 - 62 15
63 - 65 54
66 - 68 a
69 - 71 81
72 - 74 24 126
2) Find Mean by short-cut method
A) X F
2.5 4
7.5 5
12.5 7
17.5 12
22.5 7
27.6 5. 16
3) Find Mean by Step-deviation method.
A) Marks No. Of students
5 20
10 43
15 75
20 67
25 72
30 45
35 39
40 9
45 8
50 6 22.2
B) Height (in cm) No. of boys
135-140 4
140-145 9
145-150 18
150 -155 28
155- 160 24
160- 165 10
165 -170 5
170- 175 2 153.45
4) The average marks obtained in an examination by two groups of students were found to be 75 and 85 respectively. Determine the ratio of students in the two groups. If the average marks for all the students was 80. 1:1
5) There are 60 students In a class of which 25 girls. The average weight of 25 girls is 40kg and that of 35 boys is 53kg. Find the mean weight in kg of the entire class. 47.583kg
6) The mean monthly salary paid to all employees of a company was ₹ 5000. The mean annual salary to male and female employees was ₹5200 and ₹4200 respectively. Determine the percentage of males and females employed by the company. 80%, 20%
7) Mean of 25 observation was found to be 78.4. But later it was found that 96 was misread as 69. Find the correct mean. 79.48
8) The mean of 40 observations was 160. It was detected on rechecking that the value 125 was wrongly copied as 165 for the computation of the mean. Find the correct mean. 159
9) The mean age of 40 students is 16 years and the mean age of another group of 60 students is 20 years. Find out the mean age of all the 100 students combined together. 18.4
10) The mean of marks obtained in an examination by a group of 100 students is found to be 49.46. The mean of the marks obtained in the same examination by another group of 200 students was 52.32. Find the mean of the marks obtained by both the groups of students taken together. 51.37
11) the mean of 30 values was 150. it was detected on rechecking that the value 165 was wrongly copied as 135 for the computation of the mean. Find the correct mean. 151
12) Two samples of sizes 50 and 100 are given. The mean of these samples are respectively are 56 and 50. Find the mean of size 150 by combining. 52
13) The number of students in section X A and X B are 30 and 35 respectively. The mean scores of students in the mathematics test are as follows:
XA XB XA and XB(combined)
70 ? 62
find the mean score of students of X B. 55.14
14) A piece of work was done in 2, 4 and 3 days by thee men. Find the average rate of working. 36/13
23) you fly to a place X in a Boeing at a speed of 500 miles per hour and come back from X following the same route at a speed of 160 miles per hour. What is the average speed for the to and fro journey. 242.42
24) The A. M and G. M of two numbers are respectively 5 and 4. Find their H. M. 3.2
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