Find the mean and variance for the following frequency distribution.
|
Classes |
0-10 |
10-20 |
20-30 |
30-40 |
40-50 |
|
Frequencies |
5 |
8 |
15 |
16 |
6 |
|
Class |
Frequency fi |
Mid-point xi |
|
yi2 |
fiyi |
fiyi2 |
|
0-10 |
5 |
5 |
–2 |
4 |
–10 |
20 |
|
10-20 |
8 |
15 |
–1 |
1 |
–8 |
8 |
|
20-30 |
15 |
25 |
0 |
0 |
0 |
0 |
|
30-40 |
16 |
35 |
1 |
1 |
16 |
16 |
|
40-50 |
6 |
45 |
2 |
4 |
12 |
24 |
|
50 |
10 |
68 |
Mean,
