WEBVTT
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So goes that saying any time you are given a
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word problem, you should make sure you've read through
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it before you start trying to solve it out.
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Okay, but moving past that because I'm sure you
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guys already have. Before you start watching this,
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uh, this is a margin of error question,
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right? We know that from the directions that says
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find the margin very to the nearest percent. So
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when ahead and rode out The margin of error formula
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here, which is two times the square root of
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p, represents our percent of people that responded a
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certain way times the quantity of one minus that same
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p divided by n our sample size. Well,
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we're given two pieces of information here. Okay?
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We're told that 46% of the 800 randomly selected people
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responded a certain way. 46% would mean that probably
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needs to be R P. Because P is the
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variable that is supposed to be given to us as
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a percent. En is the size of our sample
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, which should be just a total number should be
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just a total of how many people or how many
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? Whatever were surveyed that sort of thing. Okay
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, so that would certainly make sense that 800 would
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be in because it tells us that's how many people
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were randomly selected. That's the total of people.
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Okay, so we've been given our information that we
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can't use 46% the way it is right now,
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because first, we need to change it to a
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decimal. Well, you change percent to a decimal
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is dividing by 100 46% divided by 100 would give
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me 1000.46 Okay, that's what I'm going to use
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for this formula. Meaning we would have. Our
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margin of air is equal to to times square root
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of RP, which is now 0.46 times the quantity
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of one minus that exact same p 10.46 And all
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of that is divided by N. Our sample size
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, which is 800 now we have to do is
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plug that into our calculator to figure out what the
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answer should be. If you plug it into your
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calculator correctly, you should get zero point 03 five
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. Looks like that's great, but that's not a
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final answer, because that is in decimal form.
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We were asked to give our margin of error to
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the nearest percent. Well, if dividing by 100
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changes a percent to a decimal, then the opposite
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of that multiplying by 100 should change a decimal to
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a percent right, so 0.35 times 100 would be
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3.5. That's great. So for our margin of
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error, it did say to the nearest percent.
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It didn't say anything about decimals, so we want
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to get a whole number here. Well, if
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it's five or higher, you are supposed to round
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up, so 3.5 would round up 24% and that
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would be our margin of error here.