Sampling Distributions

Parameters describe populations and statistics describe __________.

• parameters

• means

• samples

• results

From a large group of people who each signed a card saying they intended to quit smoking, 1000 people were randomly selected. It turned out that 210 (21%) of the selected individuals had not smoked over the past 6 months.

Identify the parameter in this example

• The 1000 people randomly selected

• all people who signed a card saying they intended to quit smoking.

• the true proportion of the population who quit smoking

• the proportion from the sample who quit smoking.

Each month, the Current Population Survey inter-views randomly selected individuals in about 60,000 U.S. households. One of its goals is to estimate the national unemployment rate. In December 2019, 3.5% of those interviewed were unemployed.

Identify the Sample

• all individuals in US households

• the individuals from 60,000 US households that are interviewed

• the true proportion of the US population who are employed

• The proportion of the sample who were unemployed.

Identify the statistic in the following.

How much do gasoline prices vary in a large city? To find out, a reporter records the price per gallon of regular unleaded gasoline at 10 randomly selected gas stations in the city on the same day. The range of the prices for these 10 stations is 25 cents.

Identify the population in the following.

On Tuesday, the bottles of iced tea filled in a plant were supposed to contain an average of 20 ounces of iced tea. Quality-control inspectors selected 50 bottles at random from the day’s production. These bottles contained an average of 19.6 ounces of iced tea.

Identify the parameter of the following

A production run of ball bearings is supposed to have a mean diameter of 2.5000 centimeters. An inspector randomly selects 100 bearings from the container and calculates a mean diameter of 2.5009 centimeters.