SOLUTION: 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

Algebra ->  Equations -> SOLUTION: 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      Log On


   

Question 476115: 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 ankor@dixie-net.com(22740) About Me  (Show Source):
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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.
:
Let s = total number of students
Let b = original number of boys
:
"the percentage of boys in a particular class is 60%."
b = .6s
:
"six girls move away, and are replaced in the class by six boys; this makes the class roster 75% boys."
b + 6 = .75s
Replace b with .6s
.6s + 6 = .75s
6 = .75s - .6s
6 = .15s
s = 6%2F.15
s = 40 students total
then
.6(40) = 24 boys originally
and
.4(40) = 16 girls originally