I have to do the CSET Multiple Subject on Saturday. I have been getting this question several times and I wanted to see what people think.
In a high school, there are 1200 students. 56% of those students are in ninth or tenth grade. 1/3 of those students are in eleventh grade. How many are in 12 grade?
Thanks in advance!
So what you would do is what we call the process of elimination. This is a basic algebra question, so first consider this. What do we know? We know how many students (1200), we know that the population of the seniors is total students minus 9th, 10th, and 11th grade. We also know how many people are in 9th, 10th, and 11th grade. What we do not know is the 12 grade population. So we would call that x. We can set it up like this:
x=1200-((.56(1200))+(1/3(1200)))
This, to simplify it, is just twelfth graders are equal to: amount of students minus 9th and 10th graders minus 11th graders. TO do this in your head, it would look like:
there are 1200 students. 56% is equal to ___. 1/3 of 1200 students is equal to ___. 1200 minus( ___+___ )is equal to how many 12th graders there are.
Algebraically, it would be:
x=1200-((.56(1200))+(1/3(1200)))
x=1200- (672 + 400)
x=128
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