Question

If the mean of the following frequency distribution is 91, find the missing
frequencies (1, 2):
Class interval Frequency

0 – 30 12
30 - 60 21
60 - 90 f1
90 --120 52
120 – 150 f2
150 - 180 11
Total
150​

Answer 1

missing frequencies f1 = 34 and f2= 20

Step-by-step explanation:

mean = 91

in continuous distribution  xi is the class interval

class interval = $\frac{upper limit + lower limit }{2}$

∑fi= 150

12+21+ f1+ 52+ f2+ 11 = 150

f1+f2= 54...(1)

∑fixi= 180+ 945+ 75 f1 + 5460+ 135 f2 + 1815

= 8400+ 75 f1 + 135 f2...(2)

mean = $\frac{\sum fixi}{\sum fi}$

91 = $\frac{8400+ 75 f1 + 135 f2}{150}$

5250 = 75 f1 + 135 f2

1050= 15 f1 + 27 f2 ...(3)

solving eq(1) and (3)

we get

F1 = 34

F2 = 20

hence , the missing frequencies f1 is 34 and f2 is 20

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https://brainly.in/question/9220404

Answer 2

Step-by-step explanation:

thx.......

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