Find the mean of the following frequency distribution.
Class-Interval |
0-8 |
8-16 |
16-24 |
24-32 |
32-40 |
Frequency |
8 |
10 |
15 |
9 |
8 |
Class-Interval (C.I.) |
Frequency (fi) |
Class-mark (xi) |
(fixi) |
0 - 8 |
8 |
4 |
32 |
8 - 16 |
10 |
12 |
120 |
16 - 24 |
15 |
20 |
300 |
24 - 32 |
9 |
28 |
252 |
32 - 40 |
8 |
36 |
288 |
Σfi = 50 |
Σfixi = 992 |
Now,
Hence, (he mean of frequency distriution is 19.84.
If the values of x or f are large, the calculation of mean by the direct method is quite lengthy and time consuming so, to minimize the time involved in calculation, we prefer assumed mean method.
Find the value of P, if the mean of the following distribution is 18.
x: |
13 |
15 |
17 |
19 |
20 + p |
23 |
f: |
8 |
2 |
3 |
4 |
5p |
6 |
The following table shows markes scored by 140 students in a examinations.
Marks |
0-10 |
10-20 |
20-30 |
30-40 |
40-50 |
No. of Sutdents |
20 |
24 |
40 |
36 |
20 |
Find the mean of the following data
Class-lnterval |
15-25 |
25-35 |
35-45 |
45-55 |
55-65 |
Frequency |
60 |
35 |
22 |
18 |
15 |
The following table represents the wages of 50 workers in a factory.
Wages (in Rs.) |
1450 |
1475 |
1500 |
1525 |
1550 |
No. of workers |
12 |
13 |
7 |
10 |
8 |
The following table represents the expenditure on the usage of water by 70 families in a locality. Find the average expenditure per family.
Exp. water (in Rs.) |
15-20 |
20-25 |
25-30 |
30-35 |
35-40 |
40-45 |
45-50 |
50-55 |
No. of families |
7 |
8 |
7 |
8 |
10 |
15 |
7 |
8 |
The following table shows marks scored by 140 students in an examination.
Marks |
0-10 |
10-20 |
20-30 |
30-40 |
40-50 |
No. of students |
20 |
24 |
40 |
36 |
20 |
Calculate mean marks by Step Deviation Method.
The mean of the following frequency distribution is 62.8 and the sum of all frequencies is 50. Compute the missing frequency f1 and f2.
C.I. |
0-20 |
20-40 |
40-60 |
60-80 |
80-100 |
100-120 |
Total |
f |
5 |
f1 |
10 |
f2 |
7 |
8 |
50 |
The mean of the following frequency distribution is 132 and the sum of observations is 50. Find the missing frequency f1 and f2.
Class |
0-40 |
40-80 |
80-120 |
120-160 |
160-200 |
200-240 |
Freq. |
4 |
7 |
f1 |
12 |
f2 |
9 |
The mean of the following frequency table is 53. But the frequencies f1 and f2 in the classes 20-40 and 60-80 arc missing. Find the missing frequencies.
Age (in years) |
0-20 |
20-40 |
40-60 |
60-80 |
80-100 |
Total |
Number of people |
15 |
f1 |
21 |
f2 |
17 |
100 |