The mean marks (out of 100) of boys and girls in an examination are 70 and 73 respectively. If the mean marks of all the students in that examination is 71, find the ratio of the number of boys to the number of girls
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Total no. Of students = x+y
Let no. Of boys = x
and no. Of girls = y
Mean marks of boys = 70
Total no. of marks by boys =70x
Mean marks of girls = 73
Total no. Of marks by girls =73y
Mean marks of all students = (70x + 73y)/(x+y)
71 = (70x +73y)/(x+y)
71x + 71y = 70x + 73y
71x-70x =73y-71y
x=2y
x/y=2/1
x:y= 2:1
Let no. Of boys = x
and no. Of girls = y
Mean marks of boys = 70
Total no. of marks by boys =70x
Mean marks of girls = 73
Total no. Of marks by girls =73y
Mean marks of all students = (70x + 73y)/(x+y)
71 = (70x +73y)/(x+y)
71x + 71y = 70x + 73y
71x-70x =73y-71y
x=2y
x/y=2/1
x:y= 2:1
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