1.

The marks obtained out of 50, by 102 students in a Physics test are given in the frequency table below: Marks (x):152022242530333845 Frequency (f):58112023181331Find the average number of marks.

Answer»

Let the assumed mean (A) = 25

 Marks (xi) Frequency (fi)ui = xi - A = xi - 25fiui
155-10-50
208-5-40
2211-3-33
2420-1-20
252300
3018590
33138104
3831339
4512020
 N = 102\(\sum\)fiui = 110

Average number of marks = A + \(\frac{\sum f_iu_i}{N}\)

\(=25+\frac{110}{102}=\frac{2550+110}{102}\)

\(=\frac{2660}{102}=26.08\) (approx)



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