AP Stat Sampling Distribution Means and Proportions

Suppose we have a population that is 49% male.  If we take a random sample from that population and determine the percent of our sample that is male, we refer to this proportion as...

• p

• p-hat
  

• the sample mean

• the sampling distribution

A sample is taken of 200 people. The number of people who own a dog was 80.
What is the sample proportion?

• 80

• 0.8

• 0.4

• 35%

What does this formula do?

• Calculates Standard Deviation

• Checks if the samples are independent

• Checks Normality

• Calculates Probabilities

Identify the population

• 20 game pieces

• p = 25%

• p-hat = 15%

• All game pieces

Identify the sample

• 20 game pieces

• 25%

• 3 instant winners

• All game pieces

Identify the parameter

• 20 game pieces

• p = 25%

• 3 instant winners

• p-hat = 3/20 = 15%

Identify the statistic

• 20 game pieces

• p = 25%

• 3 instant winners

• p-hat = 3/20 = 15%

What does the dot above .05 represent?

• 5% of the sample proportions had 1 instant winner out of 20.

• In a single sample of 20 game pieces, 1/20 (5%) were instant winners.

• There is a .05 chance of getting 1 instant winner in a sample of 20 pieces.

Would it be unusual to get a sample proportion of .60 or higher? Explain

• Yes because only 1 out the 100 sample proportions was 60%. 0.01 is unusual.

• Yes because if it is possible, it can't be unusual.

A poll asked a random sample of 1012 adults what they do with the milk in their cereal bowl after they have eaten. Let  p-hat be the proportion of people in the sample who drank the cereal milk. A spokesman for the dairy industry claims that 70% of all adults drink their cereal milk. Find the probability that at most 67% of those sampled drink their cereal milk.

• .0188

• .9812

• .0342

• .6512