Find the mean from the following frequency distribution of marks at a – InterviewSolution

InterviewSolution

1.

Find the mean from the following frequency distribution of marks at a test in statistics: Marks (x):5101520253035404550 No. of students (f):15508076724539986

Answer»

Let the assumed mean (A) = 25

Marks (x_i)	No. of students (f_i)	u_i = x_i - A = x_i - 25	f_iu_i
5	15	-20	-300
10	50	-15	-750
15	80	-10	-800
20	76	-5	-380
25	72	0	0
35	45	5	225
40	39	10	390
45	9	15	135
45	8	20	160
50	6	25	150
	N = 400		\(\sum\)f_iu_i= -1170

Mean = A + \(\frac{\sum f_iu_i}{N}\)

\(=25+\frac{-1170}{400}=\frac{1000-1170}{400}\)

\(=22.075\)

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