Transcript Statistics

Statistics
Tutorial
Statistics
• Probability and Statistics can be very
complicated, but we are going to focus on the
more basic problems such as mean and median.
We will also show how to solve a very simple
probability problem.
• Let’s get started with a couple of definitions:
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• The mean of a set of numbers is the average. You can
find the mean or average of a set of numbers by adding
them all together and dividing the sum by the amount of
numbers you added together.
• The median of a set of numbers is the middle number.
If you list all the numbers in order, the median is the
middle of the list. That’s easy if it is an odd amount of
numbers. But what if you have an even amount of
numbers? In that case, average the two numbers in the
middle.
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Mean Examples
Let’s find the mean of the following sets of numbers.
24, 37, 39, 12, 88
First we add all the numbers together.
24 + 37 + 39 + 12 + 88 = 200
Now since there are 5 numbers, we divide the answer
by 5
• 200 / 5 = 40
• So the mean of 24, 37, 39, 12, 88 is 40
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• Let’s try another one. What is the mean of the
following numbers?
• 17, 83, 52, 25, 23, 70
• 17 + 83 + 52 + 25 + 23 + 70 = 270
• 270 / 6 = 45
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• Median Examples
• Now lets find the median using the same numbers as
above.
• 24, 37, 39, 12, 88
• First we need to put them in numerical order.
• 12, 24, 37, 39, 88
• Now it’s easy to see the middle number, which is 37
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• That was easy since we had an odd amount of
numbers. But what if we have an even amount of
numbers? Remember what to do?
• Let’s find the median of these numbers.
• 17, 83, 52, 26, 23, 70
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• Once again, we need to put them in numerical order.
• 17, 23, 26, 52, 70, 83
• However, since we have no number directly in the
middle, we take the number on either side of the middle
and average them together…or we find the mean of
those two numbers.
• 26 + 52 = 78
• 78 / 2 = 39
• So the median of 17, 23, 26, 52, 70, 83 is 39
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• Probability Examples
• We will use the same example here that you saw
in the Practice Test and explain it for you.
• Problem: If you roll a die once, what are the
chances that you would get a 5?
• First we know that dice have 6 sides with a
different number on each side.
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• Since there are 6 sides, and you are only
rolling it once, you have a 1 in 6 chance that
you will get a 5. We can represent this with
the fraction 1/6
• But what if you had an alien die that has eight
sides, and has the following numbers?
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• What is the probability that if I will get a 2 if I
roll this die once?
• How many twos are there? 3
• How many sides are there? 8
• So I have 3 chances in 8…or 3/8
• Using the same alien die, what is the probability
that I would get a 9 if I roll it once?
• If you came up with 1/8 you are right!
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• Looks like your chances are pretty good for this
module exam! Good Luck!
You must make a perfect score of 100% to pass.
Click here to take the exam for this module.