Question

A department store, on average, has daily sales of 28,651.79. the standard deviation pf sales is $1000. On Tuesday, the store sold $36,211.08 worth of goods. Find Tuesday's Z-score. Was Tuesday an unusually good day?

Answer 1

Tuesday's Z-score is 7.56

Explanation:

We are given that a department store, on average, has daily sales of 28,651.79 and the standard deviation of sales is $1000.

Also, it is given that on Tuesday, the store sold $36,211.08 worth of goods.

Let X = Daily sales of goods

So, X ~ N(
`\mu = 28,651.79, \sigma^(2) =1000^(2)`)

The z-score probability distribution is given by;

Z =
`(X-\mu)/(\sigma)` ~ standard normal N(0,1)

Now, Tuesday,s Z-score is given by;

Z =
`(36,211.08-28,651.79)/(1000)` = 7.56

Yes, Tuesday was an unusually good day as on this day more worth of sales takes place as compared to the average daily sales of $28,651.79 .