SOLUTION: the average mark scored by students in a class is 65. the average mark of girls is 80. average mark of boys is 60. Find the percentage of boys in that class.

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Question 888914: the average mark scored by students in a class is 65. the average mark of girls is 80. average mark of boys is 60. Find the percentage of boys in that class.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
100%2A65=X%2A60%2B%28100-X%29%2A80
6500=60X%2B8000-80X
-20X=-1500
X=75
75% are boys, 25% are girls.