x | 10 | 20 | 30 | 40 | 50 | 60 | Total |
f | 4 | f2 | 8 | f1 | 3 | 4 | 35 |
xi | fi | xifi |
10 | 4 | 40 |
20 | f2 | 20f2 |
30 | 8 | 240 |
40 | f1 | 40f1 |
50 | 3 | 150 |
60 | 4 | 240 |
∑fi=35 | ∑fixi=670+20f2+40f1 |
mean=∑fixi∑fi⇒34=670+20f2+40f135
Or, 1190=670+20f2+40f1
Or, 40f1+20f2=520
Or, 2f1+f2=26 ....... (1)
Also, Σfi=19+f1+f2=35⇒f1+f2=16 ........ (2)
Subtracting (2) from (1) we get,
f1=10
From eq.(2) we get,
f2=16−10=6