SOLUTION: A science class has two times as many boys as girls. During the final examination of the year, the girls average 90 points each, and the class as a whole averages 80 points per per
Algebra ->
Expressions-with-variables
-> SOLUTION: A science class has two times as many boys as girls. During the final examination of the year, the girls average 90 points each, and the class as a whole averages 80 points per per
Log On
Question 827740: A science class has two times as many boys as girls. During the final examination of the year, the girls average 90 points each, and the class as a whole averages 80 points per person. What is the average score of the boys in the class? Answer by LinnW(1048) (Show Source):
You can put this solution on YOUR website! n = total students
b = no of boys
g = no of girls
s = boys average score
b + g = n
Since two times as many boys
2g + g = n
3g = n
80n = 90g + s*b
Substitute 3g for n and 2g for b
80(3g) = 90g + s(2g)
240g = 90g + (2s)g
240g = (90 + 2s)g
divide each side by g
240 = 90 + 2s
subtract 90 from each side
150 = 2s
divide each side by 2
75 = s
The average boy score is 75
