Theorem for Means
1. Question
A family of statisticians is trying to decide if they can afford for their child to play
youth baseball. The cost of joining a team is normally distributed with a mean of
$750 and a standard deviation of $185 . If a sample of 40 teams is selected at
random from the population, select the expected mean and standard deviation of
the sampling distribution below.
Correct answer:
σx¯=$29.25
μx¯=$750
The standard deviation of the sampling distribution
σx¯=σn−−√=$18540−−√=$29.25
When the distribution is normal the mean of the sampling distribution is equal to
the mean of the population μx¯=μ=$750 .
Question
A cupcake baker is planning a supplies order and needs to know how much flour he
needs. He knows that his recipes use an average of 100 grams of flour, normally
distributed, with a population standard deviation of 15 grams. If he is consulting a
sample size of 30 recipes, select the mean and standard deviation of the sampling
distribution to help him order his supplies from the options below.
σx¯=2.74 grams
μx¯=100 grams
The standard deviation of the sampling distribution is