Question 65

The average marks of 30 students is 65; 36 students is 35 and 34 students is 45. The average marks forall the students is:

Solution

these type of questions are called as weighted average type questions.

If n1,n2,n3 are number of entries and A1,A2,A3 are averages then the total average is $$\frac{\left(n1A1\times n2A2\times n3A3\right)}{n1+n2+n3}$$

so here n1=30;n2=36;n3=34

A1=65;A2=35;A3=45

$$\frac{\left(30\times65+36\times35+34\times45\right)}{30+36+34}$$

=>4740/100

=>47.4

hence the answer is option D

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