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Question 995022: There are 150 students in grade 9. If 38% of the students are girls how many more students need to join grade 9 for the percent of the girls in grade 9 become 40%.
Please provide a clear explanation
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 150 students, 38% girls, means there are 57 girls and 93 boys, for 150*0.38=57
The current proportion of girls is 57/150, or 38%
for every girl, the numerator and the denominator are increased the same.
You want the fraction to equal 40% or 0.40
(57+x)/(150+x)=0.40.
Multiply both sides by (150+x), and the removes the denominator.
57+x=(0.40)(150+x)
57+x=60+0.40x
0.60 x=3
x=3/0.60
x=5
Add 5 girls
the new proportion is 62/155, and that is 40%..
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