Find the missing frequencies in the following frequency distribution whose mean is 50

X

10

30

50

70

90

Total

F

17

fi

32

F2

19

120

 

X

10

30

50

70

90

Total

F

17

f1

32

f2

19

120

 

Given ∑ fi = 120

⇒ 17 + f1 + 32 + f2 + 19 = 120

⇒ f1 +  f2 = 52  ...... (1)

Also,

Solving (1) and (2), we get

f1 = 28 and f2 = 24

 

 

  • 48

The mean of the following frequency table is 50. But the frequencies f 1 and f 2 in class 20 – 40 and 60 – 80 are missing. Find the missing frequencies.

Class

Frequency

fi

Mid-values

xi

f iui
0-20 17 10 –2 –34
20-40 f 1 30 –1 f 1
40-60 32 50 0 0
60-80 f 2 70 1 f 2
80-100 19 90 2 38
     

We have,

N = ∑f i = 120

⇒ 68 + f 1 + f 2 = 120

f 1 + f 2 = 52

Now,

Mean = 50

Solving equation (i) and (ii), we get

f 1 = 28 and f 2 = 24.

  • -3


I asked find the missing frequencies in the following frequencies distribution, whose mean is 50.

x

10

30

50

70

90

Total

f

17

F1

32

F2

19

120

I solve it  but it is not coming

  I solve it

Fi sum is  68+f1+f2

And fi xi  3580+30f1 +70f2

 

120 = 68+f1+f2

52 = f1+f2

120=  3580+30f1 +70f2/68+f1+f2 

After this I  can not under stand  how the answer is coming  f1 = 28 and f2 = 24

  • 11
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