The following grouped data represents the number of...

The following grouped data represents the number of customers per week who made a purchase from Edgards at Sandton, over a random sample of 40 weeks. Number of customers Number of weeks 250\text{\textendash} < 500 3 500\text{\textendash} < 750 6 750\text{\textendash} < 1000 11 1000\text{\textendash} < 1250 9 1250\text{\textendash} < 1500 7 > 1500 4 Calculate the following, using the appropriate formulae: 1.1 the mean. Interpret your answer, 1.2 the first and the third quartile, 1.3 the variance, 1.4 the skewness coefficient. Comment on the shape of the distribution, 1.5 the coefficient of variation.

Transcript

00:01 A firm wants to establish how long it is supposed to take to assemble a certain product.

00:05 A random sample of 13 employees is selected, and the company measures how long it takes, each of them to assemble the product, rounded to the nearest minute.

00:13 So i organized this data into a stem and leaf plot, and the first thing that we're asked to do is to find the mean.

00:22 So to find the mean, we need to find the sum of all the values divided by the number of values.

00:32 So i added all those values together, and i got 301 divided by 13, which gave me a mean of 23 .1538.

00:46 For the median, oops, i'm jumping the gun a little bit, and misnumbering.

00:52 So they didn't give us one or two.

00:54 So we jumped into three, there we go, so four.

00:59 The median is.

01:00 Now, to find the median, we got to find the middle of our data.

01:03 So there's 13 values.

01:04 So 1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6.

01:09 That makes our median this value here, which is 19.

01:19 The mode is the number that happens most often, and we can see the modes happening right here because there are three values that are 45.

01:26 So the mode is 45.

01:28 So stem and leaf plot lets us see a lot of data easily.

01:31 It helps us organize quartiles and ranges pretty easily.

01:36 So quartile 1, when we look at our lower set of data, we have one, two, three, four, five, six.

01:42 So quartile one is going to be in between 11 and 14.

01:47 So we can take 11 plus 14 and divided by two, and that's going to give us that quartile of 12 .5.

01:57 Corpile 3, let's do that one in yellow.

02:02 So quartile three is going to be right in between 30 and 45.

02:08 So again, we could take 30 plus 45 divided by two, and that's going to give us 37 .5...

Question

Please give Ace some feedback