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Question
There are 40 students in a class, out of them 15 are boys. The mean of marks obtained by boys is 33 and that for girls is 35. Find out the mean of all students in the class.
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Solution
We have,
Number of students in a class = 40
Number of boys in a class = 15,
Mean of marks obtained by boys = 33
Mean of marks obtained by girls = 35
Number of girls in the class = 40 - 15 = 25
Sum of marks obtained by boys = Mean × Number of boys
= 33 × 15
= 495
Sum of marks obtained by girls = 35 × 25 = 875
So, the mean of all students in the class = `"Sum of marks obtained by students"/"Number of students"`
= `(495 + 875)/40`
= `1370/40`
= 34.25
The mean of all students in the class is 34.25.
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