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At a certain elementary school, 10 percent of the fifth-gra
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18 Dec 2017, 12:45
18 Dec 2017, 12:45
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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%
A. 10%
B. 12%
C. 20%
D. 30%
E. 50%
Re: At a certain elementary school, 10 percent of the fifth-gra
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20 Dec 2017, 02:04
20 Dec 2017, 02:04
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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%
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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Re: At a certain elementary school, 10 percent of the fifth-gra
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29 May 2018, 06:53
29 May 2018, 06:53
1
Expert Reply
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%
A. 10%
B. 12%
C. 20%
D. 30%
E. 50%
We can let the total number of 5th grade students be 1000.
So 100 5th graders are in the band.
Now let b = the number of boys in 5th grade of the school, so 1000 - b = the number of girls in 5th grade. We can create the equation:
0.12b + 0.08(1000 - b) = 100
0.12b + 80 - 0.08b = 100
0.04b = 20
b = 20/0.04 = 2000/4 = 500
So the number of boys in 5th grade is 500/1000 = 1/2 = 50% of all 5th graders at the school.
Answer: E
