The mean marks (out of 100) of boys and girls in an exam are 70and 73.if the mean marks of all the students in that exam is71.find the ratio of the number of boys to the number of girls.
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let,the total mark of boys= b
the total mark of girls=g
total no.of boys=x
total no.of girls=y
so ,the mean mark of boys= b/x=70
the mean mark of girls=a/x=73
the mean mark of the total students in the examination=(b+g)/(x+y)=71
b=70x. g=73y.
and then,
= (70x+73y)/(x+y)=71
= 70x+73y = 71x+71y
=-x=-2y
=x=2y
=x/y=2/1
the total mark of girls=g
total no.of boys=x
total no.of girls=y
so ,the mean mark of boys= b/x=70
the mean mark of girls=a/x=73
the mean mark of the total students in the examination=(b+g)/(x+y)=71
b=70x. g=73y.
and then,
= (70x+73y)/(x+y)=71
= 70x+73y = 71x+71y
=-x=-2y
=x=2y
=x/y=2/1
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