1. Suppose that every time an Internet user visits our company\'s website, there

Question

1. Suppose that every time an Internet user visits our company's website, there is a 0.01 probability of a sale. We know that there were 30 visits to our website in the last hour but we don't know how many of those visits actually resulted in a sale. We will let S = the number of sales we made in that hour.

What is the expected value [to at least two decimal places] of S?

Continuing, what's the variance of S = the # of sales in the last hour? [to at least 2 decimal places]

Continuing, what's the standard deviation of S = the number of sales in the last hour?

Continuing, what is the probability that there were no sales at all in the last hour (that is, that S = 0)? [to at least four decimal places]

Continuing, what's the probability we made at least one sale in that hour?

Continuing, what's the probability of two or fewer sales? [four or more decimals]

Explanation / Answer

This is binomial distribution with n=30 and p=0.01

Mean=np=30*0.01=0.3

Sd=sqrt(npq)=0.545

P(x=0)=0.7397

P(x>=1)=0.2603

P(x<=2)=0.9967

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