Both parts of q40......
Attachments:
Answers
Answered by
1
Answer:
2 : 1
Step-by-step explanation:
mean = total marks / students
total students = 100 (given)
boys = x (assume)
girls = 100-x
mean of total students = 71 (given)
i,e. total marks (all) / total students = 71 ( formula)
total marks / 100 = 71
total marks = 7100
mean marks of boys = 70 (given)
i,e boys marks / x = 70
boys marks = 70x
mean marks of girls = 73 (given)
i,e..girls marks/ (100-x) = 73
girls marks = 73 (100-x)
but......
total marks = boys marks + girls marks
7100 = 70x + 73 (100-x)
3x = 200 ; x = 200/3
now...100-x = 100 - (200/3) = 100/3
hence....
x/(100-x) = (200/3) / (100/3)
x/(100-x) = 2/1
therefore....
boys : girls = 2 : 1
Similar questions