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Question 63236: Any help with this would be greatly appreciated. I'm really bad at word problems.
On the first day of school, the percentage of boys in a particular class is 60%. During the school year, six girls move away, and are replaced in the class by six boys; this makes the class roster 75% boys. Find the number of boys and girls in the class on the first day of school.
Answer by ptaylor(2198)   (Show Source):
You can put this solution on YOUR website! We can let x=total number of students
Then .6x=number of boys on the first day and
.4x=number of girls on the first day
When 6 girls move away and are replaced by 6 boys, we have .4x-6 girls left
and .6x+6 boys
We know that we now have 75% boys in the class (and 25% girls). The total number of students, of course, does not change. We can now solve this problem in one of two ways: Number of girls in the class (.4x-6) must equal 25% of the total class (.25x) or number of boys in the class (.6x+6) must equal 75% of the total class (.75x). I'll solve one and you can solve one:
.4x-6=.25x simplifying, we have
.15x=6
x=40 students in the class
.6x=.6(40)=24 boys on the first day and 16 girls
Hope this helps -----ptaylor
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