kevinkhan
Hi there,
I need a little bit of assistance with the following questions:
1. The ratio of boys to girls in a classroom is 5 to 7. If one student is select at random, what is the probability that this student is a boy?
If you're stuck, one place to start is by rewriting what they're asking you for.
The probability that a student is a boy, is the following:
number of boys / total number of students
You don't know the exact number of boys, or the exact number of students. However, you do know that 5 out of every 12 students are boys (because for every 5 boys, there are 7 girls - so, for every 5 boys, there are a total of 5+7 = 12 students). Therefore, this fraction is 5/12.
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2. Reduce the following ration 15!:14!
To reduce a ratio, divide each part of the ratio by the same number.
To reduce a ratio as much as possible, keep dividing until you can't find any more common factors to divide by.
The ratio you have here is really this:
15x14x13x12x...x3x2x1 : 14x13x12x...x3x2x1
The two sides of the ratio have a LOT of common factors you could divide by: you can divide by 14, by 13, by 12, and so on. Does that get you unstuck?
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3. The ration of pants to shirts in Raj's closet is 4:5 and Raj has fewer than 47 items in his closet. How many items does Raj's closet contain?
It's hard to say! Assuming the only items in the closet are pants and shirts (that is, he doesn't have any jackets, belts, etc.) - then, here's how you'd start with this. You know that for every 4 pants, there are 5 shirts, for a total of 9 items. So, the total number of items would have to be a multiple of 9. You can confirm this by trying some numbers:
4 pants and 5 shirts = 9 items = multiple of 9
40 pants and 50 shirts = 90 items = multiple of 9
8 pants and 10 shirts = 18 items = multiple of 9
and so on.