*+**** Marie--Woods entered math111e_Room1. Tuesday, April 3, 2007 5:45pm
*+**** Bill--Beck entered math111e_Room1. Tuesday, April 3, 2007 5:52pm
*-**** Bill--Beck left math111e_Room1. Tuesday, April 3, 2007 5:52pm
*+**** Bill--Beck entered math111e_Room1. Tuesday, April 3, 2007 5:52pm
Bill Beck>>Hi, Jim and Marie!
Marie Woods>>Hi, I looked over ch 10 and have so many questions
Bill Beck>>Well, I'm the guy with the answers!
Marie Woods>>First of all, when you get the measurements or numbers between 0 and whatever how do you come up with the figure? I don't get it
Marie Woods>>I mean the numbers in the curve?
Bill Beck>>Let's go through tonight's walkthru and maybe that will answer your questions, Marie.
Marie Woods>>Thanks
Bill Beck>>Are we all on Walk21_p1?
Marie Woods>>yes
Bill Beck>>Are you with us, Jim?
Bill Beck>>I think Jim went out for a beer.
Bill Beck>>Let's go to page 2, please.
Marie Woods>>maybe so
Bill Beck>>I've sketched the graph of this distribution.
Marie Woods>>II see this, but how do you measure the darkened area?
Bill Beck>>Notice that the high point of the graph (the mode) is at about .02 or .03
Bill Beck>>Hang in there with me, Marie.
Marie Woods>>yes
Bill Beck>>Go to page 3, please.
Marie Woods>>I will
Bill Beck>>Go to page 4, please.
*+**** Tonia--Bussey entered math111e_Room1. Tuesday, April 3, 2007 5:59pm
*+**** David--Wells entered math111e_Room1. Tuesday, April 3, 2007 5:59pm
Bill Beck>>Hi, Tonia and David!
David Wells>>hello
Bill Beck>>We're on Walk21 P4.
Bill Beck>>Go to page 5, please.
Bill Beck>>MATH 111 classes are sometimes bimodal also
Bill Beck>>Lots of As and lots of Ds
Bill Beck>>Go to page 6, please.
*-**** James--Boland left math111e_Room1. Tuesday, April 3, 2007 6:01pm
Bill Beck>>For a "normal" distribution the mean, median, and mode are the same.
Bill Beck>>We're going to spend some time looking at "normal" distributions tonight.
Bill Beck>>Go to page 7, please.
Bill Beck>>For example, if we know that the mean is 7 and the standard deviation is 2, then we know that 7+2 = 9 and 7 - 2 = 5 so we know that approximately 68% of the data lie between 9 and 5.
Bill Beck>>Go to page 8, please.
*+**** Danny--Wells entered math111e_Room1. Tuesday, April 3, 2007 6:04pm
Bill Beck>>And we know that 7+2(2) = 7+4 = 11
Bill Beck>>7 - 2(2) = 7-4 = 3
Bill Beck>>So we know that approximately 95% of the scores lie between 11 and 3.
Bill Beck>>Hi, Danny!
Danny Wells>>hello, what page are we on?
Bill Beck>>Danny, we are on Walk21 p8
Danny Wells>>thank you
Bill Beck>>Go to page 9, please.
Bill Beck>>So between 7 + 3(2) = 7 + 6 = 13
Bill Beck>>and 7 - 3(2) = 7 - 6 = 1
Bill Beck>>Thus approximately 97.5% of the scores lie between 13 and 1.
Bill Beck>>Marie wants to know where we get these figures!!!!
Marie Woods>>please, do tell
Bill Beck>>Right, Marie?
Marie Woods>>yes
Bill Beck>>Okay, let's reveal out secret.
Bill Beck>>Let's click on Tools then Table, please.
Tonia Bussey>>wow, there they are!
Marie Woods>>I had no idea
Bill Beck>>In the upper left hand corner of the table we see a graph with an area shaded red.
Marie Woods>>Lets do one wiht the table, please
Bill Beck>>That area is between some value called 0 and z
Bill Beck>>Before we get into calculating z, let's see how we read this table.
Marie Woods>>what is 0 and what is z on the table, give me an example
Marie Woods>>I see z and A
Marie Woods>>across the top of the tab le
Bill Beck>>Let's read the table, then we'll worry about calculating z, Marie.
Bill Beck>>Suppose z = .51
Marie Woods>>okay
Bill Beck>>Do you agree that A = .195?
Marie Woods>>yes
Bill Beck>>And if z = 1.15 do you agree that A = .375?
Marie Woods>>yes
Marie Woods>>I am seeing it now
Bill Beck>>It turns out that z = (x - xbar)/s
Bill Beck>>But we'll worry about that later.
Bill Beck>>Let's click on "hide 'em" please.
Bill Beck>>Go to page 10, please.
Bill Beck>>Here I'm given a shaded region between z = 0 and z = 1.2
Marie Woods>>okay
Bill Beck>>We want to use the table to determine the area of that region.
Bill Beck>>Go to page 11, please.
Bill Beck>>Do you agree that A = .385?
Bill Beck>>Do you know where I got that .385?
Bill Beck>>Hmmmmm
Marie Woods>>no
Bill Beck>>Let's click on Tools, then Table, please.
Marie Woods>>would it be reversing and finding A on the table
Tonia Bussey>>yes, i see
Bill Beck>>We need to scroll down to get z = 1.20
Marie Woods>>It appears to easy
Bill Beck>>And next to the z=1.20 do you see the A=3.85?
Marie Woods>>yes
Bill Beck>>Okay, let's click on "hide 'em" please.
Marie Woods>>move the decimals from.385 to 3.85?
Bill Beck>>This time we have a negative value for z
Bill Beck>>No, That was a typo, Marie, it should be .385
Marie Woods>>okay
Bill Beck>>On page 12, we have a negative value for z
Bill Beck>>Because of the symmetry of the normal curve, the area under the curve between z = 0 and z = -.55 is exactly the same as the area under the curve between z = 0 and z = .55
Bill Beck>>So to the area between z = 0 and z = -.55, we just look at z = .55 in our table.
Bill Beck>>What is our value?
Tonia Bussey>>.209
Marie Woods>>.209
Bill Beck>>RIGHT
Bill Beck>>Okay, let's go to page 13, please.
Bill Beck>>Go to page 14, please.
Tonia Bussey>>so anytime it is a negative, it is as if we apply it as a positive
Bill Beck>>ALWAYS sketch a graph!
Bill Beck>>Yes, Tonia.
Bill Beck>>Go to page 15, please.
Tonia Bussey>>okay, thanks
Bill Beck>>Go to page 16, please.
Bill Beck>>Hmmmmm
Bill Beck>>This time I've sketched a graph that does not touch the line z = 0
Bill Beck>>It is a "detached region."
Bill Beck>>Go to page 17 to see how we determine the area when it is detached.
Bill Beck>>abut means to touch.
Bill Beck>>Go to page 18, please.
Bill Beck>>We can use our table to determine the area between z=0 and z=1.83
Bill Beck>>Go to page 19, please.
Bill Beck>>We can use our table to determine the area between z=0 and z=.50
Bill Beck>>Life is good!
Bill Beck>>Go to page 20, please.
Marie Woods>>so far
Bill Beck>>Makes sense to me. How about you?
Marie Woods>>yes
Tonia Bussey>>yep, i get it
Bill Beck>>Go to page 21, please.
Bill Beck>>If we look at z = 1.83 in our table, we see that A = .466
Bill Beck>>Go to page 22, please.
Bill Beck>>If we look at z = .50, we see that A = .192
Bill Beck>>Go to page 23, please.
Bill Beck>>A little subtraction gives us the area of the detached region.
Bill Beck>>Make sense?
Marie Woods>>wiith the tablet was really easer than I feared
Tonia Bussey>>yes
Marie Woods>>table
Bill Beck>>Life is good when you have a copy of the table.
Bill Beck>>I'll supply the table on Test 3!
Marie Woods>>great
Bill Beck>>Okay, let's go to the last walkthru for tonight, please.
Bill Beck>>Let me know when you are on Walk22 p1, please.
Marie Woods>>there
David Wells>>there
Tonia Bussey>>i'm there
Danny Wells>>im there
Bill Beck>>Go to page 2, please.
Bill Beck>>The mean, 7.5 is at the center of the normal curve.
Bill Beck>>7.3 is to the left of 7.5
Bill Beck>>Go to page 3,please.
Bill Beck>>Here's our formula for z
Bill Beck>>I'll supply this formula on Test 3.
Bill Beck>>Go to page 4, please.
Marie Woods>>good
Bill Beck>>Notice that z is a negative number.
Tonia Bussey>>great
Bill Beck>>That just means that our score, x, is to the left of the mean, xbar.
Bill Beck>>Go to page 5, please.
Bill Beck>>For z = .13, we get A = .052
Bill Beck>>Okay?
Marie Woods>>table again?
Bill Beck>>yes
Bill Beck>>Go to page 6, please
Marie Woods>>on this problem will the negative number always be 1st
Bill Beck>>Go to page 7, please.
Marie Woods>>n the math
Bill Beck>>Sketch a graph!
Bill Beck>>The mean is in the middle of the graph
Bill Beck>>Go to page 8, please.
Bill Beck>>12 is to the right of 10
Bill Beck>>And we want the region to the right of 12, so I've shaded the graph to the right of 12.
Bill Beck>>Go to page 9, please.
Bill Beck>>Remember, our table always has regions that abut z = 0
Bill Beck>>Go to page 10, please.
Bill Beck>>This is another region that abuts z = 0
Bill Beck>>Go to page 11, please
Bill Beck>>When we have a detached region, we need to subtract!
Bill Beck>>Go to page 12, please.
Bill Beck>>1/2 of the scores are to the right of the mean, median, and mode.
Bill Beck>>Go to page 13, please.
Bill Beck>>First we calculate z, then we use the table to determine A
Bill Beck>>Go to page 14, please.
Bill Beck>>Go to page 15, please.
Bill Beck>>Make sense?
Tonia Bussey>>got it
Marie Woods>>sort of
Bill Beck>>Go back and listen to the lectures again, Marie.
Bill Beck>>Take good notes!!!
Bill Beck>>Okay, Class, that's it for tonight.
Marie Woods>>try again, where did .500 and .341 come from again?
Bill Beck>>We don't have class next week - it's spring break.
Bill Beck>>1/2 of the scores are greater than the median -- .500
Marie Woods>>do we have homework due on Tuesday
Bill Beck>>Then we calculated z = 1 for x = 12, so we used our table to get A = .341
Tonia Bussey>>As always Bill, thanks! Have a great spring break!! :)
Bill Beck>>Our next homework is due after the break.
Bill Beck>>Have a good one, Tonia!
David Wells>>good night
Tonia Bussey>>:)
*-**** David--Wells left math111e_Room1. Tuesday, April 3, 2007 6:37pm
Bill Beck>>G'night, David
*-**** Tonia--Bussey left math111e_Room1. Tuesday, April 3, 2007 6:37pm
*+**** Lisa--Despanza entered math111e_Room1. Tuesday, April 3, 2007 6:37pm
Danny Wells>>bye, night
*-**** Danny--Wells left math111e_Room1. Tuesday, April 3, 2007 6:37pm
Marie Woods>>help
Marie Woods>>where does .500 come from again? on the table
Lisa Despanza>>I was late, I guessed I missed everything
*+**** Bill--Beck entered math111e_Room1. Tuesday, April 3, 2007 6:38pm
Bill Beck>>Lost my connection
Bill Beck>>Are you still with me?
Lisa Despanza>>yes
Marie Woods>>I see 1 is .341, but which .500 is used?
Bill Beck>>Marie, don't forget about the median
Bill Beck>>The median is the point such that 50% of the scores are greater than the median and 50% of the scores are less than the median.
Bill Beck>>For a normal curve the median, mean, and mode are the same.
Bill Beck>>That's where the .500 comes from.
Bill Beck>>Okay?
Marie Woods>>I know you want to go, but I just don’t see it
*-**** Lisa--Despanza left math111e_Room1. Tuesday, April 3, 2007 6:42pm
Bill Beck>>Marie, do you remember the definition of median?
Marie Woods>>what number on the table is .500, maybe if I see it I will get iit
Marie Woods>>I will check the definition again
Bill Beck>>I'm talking about our lesson on mean, median and mode, Marie.
Marie Woods>>yes
Bill Beck>>Do you remember how we determined the median and what that number represented?
Marie Woods>>I need to review
Bill Beck>>The median is the number such that 1/2 of the scores are less than the median and 1/2 of the scores are greater than the median.
Marie Woods>>okay
Bill Beck>>Thus I don't need to use the table to determine that score.
Bill Beck>>I know that 1/2 or .500 of the scores are less than the median and that 1/2 or .500 of the scores are greater than the median.
Bill Beck>>I didn't use the table at all for that value.
Marie Woods>>then its .250 either way, right? equaling .500
Bill Beck>>No, it's .500 to the left of the median and .500 to the right of the median for 1.00
Marie Woods>>I see now, we are usng.1 not 1 as a whole, so its 1 half f 1
Marie Woods>>of 1
Bill Beck>>That's right
Marie Woods>>finially, sorry to keep you, have a great break
Marie Woods>>thanks
Bill Beck>>No problem, Marie, have a good break.
Bill Beck>>G'night
Marie Woods>>good nght
*-**** Marie--Woods left math111e_Room1. Tuesday, April 3, 2007 6:47pm
*-**** Bill--Beck left math111e_Room1. Tuesday, April 3, 2007 6:47pm
*-**** Bill--Beck left math111e_Room1. Tuesday, April 3, 2007 6:55pm
******************************************************************************
Session in math111e_Room1 ended. (all participants have left).
Tuesday, April 3, 2007 6:55pm
******************************************************************************
*^****************************************************************************
New session has begun in math111e_Room1.
Wednesday, April 4, 2007 2:00pm
*^****************************************************************************
*+**** Mira--Hickson entered math111e_Room1. Wednesday, April 4, 2007 2:00pm
*-**** Mira--Hickson left math111e_Room1. Wednesday, April 4, 2007 2:01pm
******************************************************************************
Session in math111e_Room1 ended. (all participants have left).
Wednesday, April 4, 2007 2:01pm
******************************************************************************
*^****************************************************************************
New session has begun in math111e_Room1.
Wednesday, April 4, 2007 2:22pm
*^****************************************************************************
*+**** Antoinette--Johnson entered math111e_Room1. Wednesday, April 4, 2007 2:22pm
*-**** Antoinette--Johnson left math111e_Room1. Wednesday, April 4, 2007 2:22pm
******************************************************************************
Session in math111e_Room1 ended. (all participants have left).
Wednesday, April 4, 2007 2:22pm
******************************************************************************