7. Calculate the arithmetic mean from the following:
X:
fi
40 to 30
10
-30 to 20
28
20 to 10
30
10 10 0
42
0 to 10
65
10 to 20
20 to 30
180
10
[Ans. X-4.287]
Date
X
X
F
Fx
-4oto-30
-35
10
-350
-30 to-20
-25
28
-700
-20 to -10
-15
30
-450
-10 to 0
-5
42
-210
o to 10
5
65
325
10 to 20
15
180
2700
20 to 30
25
10
250
365
15655
X = fx
1565
365
= 4.287