FINDING MEAN 1

In Mathematics test the following marks were recorded.

marks	31-40	41-50	51-60	61-70	71-80	81-90
No. of students	5	7	14	10	9	5

Calculate the mean.

Solution

Here you are required to produce the frequency distribution table.

Class interval	Class mark (x)	Frequency(f)	fx
31-40	35.5	5	177.5
41-50	45.5	7	318.5
51-60	55.5	14	777
61-70	65.5	10	655
71-80	75.5	9	679.5
81-90	85.5	5	427.5
		∑f = 50	∑fx = 3035

Mean = ∑fx

               ∑f

Mean = 3035

               50

Mean =  60.7

         

Hence Mean =  60.7

TRY THIS....................

In biology test the following marks were recorded.

interval	20-24	25-29	30-34	35-39	40-44	45-49
No. of students	5	7	16	8	9	5