Using glasses or not?

Algebra Level 2

In a classroom, there are 40% of the students who are boys, 55% of those boys and $66 \frac {2} {3}$ % of those girls are wearing glasses. The amount of students who are not wearing glasses are 76 students. What is the difference between the boys who are wearing glasses and the boys who doesnt?

8 12 15 7

2 solutions

Bk Lim
Dec 18, 2014

Boys with spec = 0.4x0.55=0.22 class

Boys without spec = 0.4x0.45=0.18 class

Girls with spec = 3/5 x 200/3 = 0.40 class

Girls without spec = 3/5 x 100/3 = 0.20 class

0.38 class =76 students, means 200 students in class.

The difference btw boys with and without spec = 0.04 class = 8

Mohd Naim Mohd Amin
Dec 8, 2014

Hello & peace be upon you...

Let's B= boys , G= girls, x = total ,

As x = B + G , B(40%) = 0.4x , G(60%) =0.6x,

So, for boys that wore glasses(55%) = a,

a = 0.55(0.4x) = 0.22x, therefore , boys are not wearing glasses is,

b = 0.4x - 0.22x = 0.18x,

As for girls wore glasses(200/3%) = c,

c = (2/3)0.6x = 0.4x,

d= not wearing glasses = 0.2x,

Given total boys and girls are not wearing glasses is 76,

b + d = 0.18x + 0.2x = 76

x = 76 / 0.38 = 200,

Now , you could get the answer,

As for a - b = 0.22x - 0.18x = ?.....just substitute x = 200...

Thanks....

Using glasses or not?

2 solutions

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