1.

(CBSE 2006r. The mean of the following distribution is 53. Find the value off:Class 0-20 20-40 40-60 60-80Frequency172832fi1. Find the mean of the following frequency distribution:80-10019[CBSE 2006​

Answer»

ANSWER:

Step-by-step explanation:CALCULATION of Mean  

CLASSES Mid-values

(x  

i

​  

) Frequency

(f  

i

​  

) d  

i

​  

=x  

i

​  

−50 u  

i

​  

=  

20

x  

i

​  

−50

​  

 f  

i

​  

u  

i

​  

 

0-20 10 15 -40 -2 -30

20-40 30 18 -20 -1 -18

40-60 50 21 0 0 0

60-80 70 29 20 1 29

80-100 90 17 40 2 34

∑f  

i

​  

=100   ∑f  

i

​  

u  

i

​  

=15

We have,

A= 50, h= 20, N= 100 and ∑f  

i

​  

u  

i

​  

=15

∴Mean=A+h[  

N

1

​  

∑f  

i

​  

u  

i

​  

]

⇒Mean=50+20×  

100

15

​  

 

$$\Rightarrow  Mean = 50+3= 53


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