2) Suppose that the store chain of Electronics Plus sells...

2) Suppose that the store chain of Electronics Plus sells extended warranties to 20% of customers who purchase electronic devices. A local Seattle store samples 300 customers from their data base. a. What proportion of customers would they expect to have purchased extended warranties? b. What is the standard deviation of the sample proportion? c. What shape would you expect the sampling distribution of the proportion to have? d. Would you be surprised to find out that in a sample of 300, 40 of the customers purchased extended warranties? Explain. What might account for this high percentage?

Transcript

00:01 Hi, i'm david and i'm here to help you answer your question.

00:04 Now let me bring up your question here.

00:07 In this question here, we'll discuss about the sampling distribution of the sample proportion.

00:12 Let me remind you that if we have the n is large, and then the sample proportion be hot will follow by the normal, with the mean and be hot equal to the population proportion.

00:26 Standard division will be hot equal to square root to the p times 1 minus b, divided by n.

00:31 In this question here we're given the 20 % of the customer who purchase electronic device.

00:39 So we have p equal to the 0 .2.

00:42 We have the sample and equal to the 300.

00:45 And the question i asked let you find the expected proportion of the p heart.

00:53 So means, i don't want to find the mean of the p heart.

00:56 So therefore the answer here change equal to the p and it will equal to the 0 .2.

01:02 For the question b, want to find the standard division of the sample proportion.

01:09 So standard division of p hot by the formula it will equal to the square root on the p times 1 minus p divided by n.

01:17 Therefore we have the 0 times 1 minus 0 divided the 300.

01:23 Then we can equal to the 0 .0 231.

01:33 Now for the c, what is the sap of the summary distribution? so because we have the p -hat followed by the normal with the mean equal to the 0 -1 -2, standard division equal to the 0 -2 -3 -1, so therefore the sharp it will be like a bell -sab.

02:00 And for the question d, once you find is a surprise to us that to find the sample 3040 on the customer purchase extended guarantee.

02:11 It means then when you find the probability that the p...

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