找到速率 (比例的應用 英語)
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找到速率 (比例的應用 英語): 找到速率 (比例的應用)
- Jayda takes 3 hours to deliver 189 newspapers
- on her paper route.
- What is the rate per hour at which she
- delivers the newspaper?
- So this first sentence tells us that she delivers, or she
- takes, 3 hours to deliver 189 newspapers.
- So you have 3 hours for every 189 newspapers.
- That's what the first sentence told us.
- But we want to figure out the rate per hour, or the
- newspapers per hour, so we can really just flip this rate
- right here.
- So if we were to just flip it, we would have 189 newspapers
- for every 3 hours, which is really the same information.
- We're just flipping what's in the numerator and what's in
- the denominator.
- Now we want to write it in as simple as possible form, and
- let's see if this top number is divisible by 3.
- 1 plus 8 is 9, plus 9 is 18.
- So that is divisible by 3.
- So let's divide this numerator and this denominator by 3 to
- simplify things.
- So if you divide 189 by 3.
- Let's do it over on the side right here.
- 3 goes into 189.
- 3 goes into 18 six times.
- 6 times 3 is 18.
- Bring down the 9.
- 18 minus 18 was nothing.
- 3 goes into 9 exactly three times.
- 3 times 3 is 9, no remainder.
- So if you divide 189 by 3, you get 63, and if you divide 3 by
- 3, you're going to get 1.
- You have to divide both the numerator and the denominator
- by the same number.
- So now we have 63 newspapers for every 1 hour.
- Or we could write this as 63 over 1 newspapers per hour.
- Or we could write this as 63, because 63 over 1 is the same
- thing as 63 newspapers per hour.