Question

10) Find the mean for the following data
30-40
40-50
50-60
60-70
10-20 20-30
f
2
3
7
6
6
6​

Answer 1

Step-by-step explanation:

Solution :

With the given distribution , xi=35,45,55,65,75,85,95

fi=3,7,12,15,8,3,2

∴xifi=105,315,660,975,600,255,190

∴∑fi=50

∑xifi=3100

∴Mean(X¯¯¯)=∑xifi∑fi=310050=62

Now, |xi−x¯|=27,17,7,3,13,23,33

|xi−x¯|2=729,289,49,9,169,529,1089

∴|xi−x¯|2fi=2187,2023,588,135,1352,1587,2178

∴ Variance, (σ)2=∑|xi−x¯|2fi∑fi=1005050=201

Standard deviation, (σ)=201−−−√≅14.177.

Answer 2

Answer:

10-20 15 12 180

20-30 25 3 75

30-40 35 3 105

40-50 45 2 90

50-60 55 10 550

60-70 65 10 650

I hope u happy for this..