Carcass wrote:
At a certain elementary school, 10 percent of the fifth-grade students are members of the school band. If 12 percent of the fifth-grade boys and 8 percent of the fifth-grade girls are members of the band, what percent of the fifth-grade students at the school are boys?
A. 10%
B. 12%
C. 20%
D. 30%
E. 50%
Here let boys = b and girls = g
and total students = 100
i.e. b + g =100 --------- equ 1
10% of the students are member of school band = 10% of 100 = 10 students.
out of which 12% are boys and 8% are girls
i.e. 0.12b + 0.08g = 10 ----------equ 2
Now multiplying equation 1 by 0.12,
0.12b + 0.12g =12 ---------equ 3
equ 2 - equ 3
0.04g = 2
or g = 50
Hence b= 50 (from equation 1)
Therefore there are 50% fifth-grade students at the school are boys. option E
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