Question

In the following frequency distribution, if the arithmetic mean is 42, find the missing

frequency. [3]

SALARIES

(Rs.)

5-15 15-25 25-35 35-45 45-55 55-65 65-75

NO. OF

EMPLOYEES

5 6 7 x 4 3 9​

Answer 1

Explanation:

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Answer 2

Find the mean of the following data, using direct method:

Class 25−35 35−45 45−55 55−65 65−75

Frequency 6 10 8 12 4Class Interval Frequency f

i

Mid-Value x

i

f

i

x

i

25−35 6 30 180

35−45 10 40 400

45−55 8 50 400

55−65 12 60 720

65−75 4 70 280

∑f

i

=40 ∑f

i

x

i

=1980

Mean =

∑f

i

∑f

i

x

i

=

40

1980

=49.5