Question

Please make sure you show how you get the z-score please (that's what i'm most confused about)

In a campaign to improve the freshness of its dairy products, a large supermarket chain conducted a random sample of 100 of its stores. In each store, a carton of milk (among other things) was randomly drawn from the shelf and X, the number of days remaining until its expiration date, were recorded. In the whole population of milk cartons in all the stores, suppose X has a mean of 5.6 days and a standard deviation of 2.7 days. What is the chance that the sample mean will be between 5.4 and 5.8 days? Name the result that you are using to be able to quantify this probability

Answer 1

Let denote the sample mean

We are given :

Required probability = Probability that the sample mean will be between 5.4 and 5.8 days = P( 5.4 < < 5.8)

We use Excel function "NORMSDIST()" as :

Hence,

Chance that the sample mean will be between 5.4 and 5.8 days = 0.5411