Question

The average score of girls in Class XII examination in a
school is 73 and that of boys is 71. The average of score in
class XII examination of the school is 71.8. The percentage
of boys in class XII of the school is:
(a) 56%
(6) 60%
(c) 65%
(d) None of these​

Answer 1

Answer:

Let the number of boys be x and that of girls be y.

Then,

total score of boys = 71x

total score of girls = 73y

Therefore, 71x+73y(x+y)=71.8

=> 71x+73y=71.8x+71.8y

0.8x = 1.2 => xy=1.20.8=32

Therefore, Percentage of girls in the class

=25×100 = 40%

Answer 2

avg score of girls = 73%

avg score of boys = 71%( gender discrimination)

the overall score was 71.8%

Let the % of girls be x

now average score of the class =

(73× percentage of girls in the class + 71× percentage of boys in the class)/ (number of observations that is) 2

ATQ 71.8 = (73/100 × x + 71 /100 × 100- x)/2

= [(73x+71x)/100]/2

7180=144x × 2

7180= 288x

x = 28.93

hence the class has 28.93% of girls and 71.07% of boys

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