00:02
Okay, so we have the temperature and we have the ice cream.
00:04
They gave us the mean and standard deviation for each the temperature and the ice cream cells.
00:13
And we are using temperature as x and sales as y.
00:23
Before we can find the slope and the y intercept, we want to find the correlation.
00:28
So correlation is a real pain to calculate by hand.
00:34
So i suggest use an excel for your calculator.
00:39
I'm using excel and i just type in equals and then start typing in correlation.
00:45
And then it wants an array and another array.
00:48
So it's the first list, comma, my y list.
00:55
And that gives me the correlation of the data.
01:00
Okay.
01:01
Now to find the slope, i can use this formula here.
01:05
B is equal to r times the standard deviation of y over the standard deviation of x.
01:12
So i'm going to do my correlation times standard deviation of y, which is the ice cream sales, divided by standard deviation of x, which is the temperature.
01:31
So that gives me a slope of 34 .37.
01:37
So that means for each additional degree, ice cream cells go up by about 34 .37.
01:58
And what were they measuring it in? oh, dollars.
02:03
So about $34 and 37.
02:15
So each degree gets us another $34, give or take.
02:19
Okay, and then to find the y intercept, i'm going to do the mean of y.
02:26
So i have to do equals and the mean of y minus the slope times mean of x.
02:40
And that gives us a y intercept of negative 2, 29, 475.
02:47
Okay, so that takes care of our correlation and our slope and our y intercept...