In a class of 100 students there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class is 72, then what is the average of the girls?
A.
73
B.
65
C.
68
D.
74
Answer :
65
Solution :
Total student= 100 ;
for 70 stds. total marks $$ = 75 \times 70 = 5250$$
⇒ Total marks of girls $$= 7200 - 5250 = 1950$$
Average of girls $$ = \frac{{1950}}{{30}} = 65$$
Releted MCQ Question on Statistics and Probability >> Statistics
Releted Question 1
Select the correct alternative in each of the following. Indicate your choice by the appropriate letter only.
Let $$S$$ be the standard deviation of $$n$$ observations. Each of the $$n$$ observations is multiplied by a constant $$c.$$ Then the standard deviation of the resulting number is
Consider any set of 201 observations $${x_1},{x_2},.....\,{x_{200}},\,{x_{201}}.$$ It is given that $${x_1}\, < \,{x_2}\, < \,.....\, < {x_{200}}\, < {x_{201}}.$$ Then the mean deviation of this set of observations about a point $$k$$ is minimum when $$k$$ equals
In a class of 100 students there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class is 72, then what is the average of the girls?