Chapter 7 Multiple Choice Practice

According to DuPont 2012 Global Automotive Color Popularity Report, 23% of all cars manufactured in 2012 were white.  In a random sample of 100 cars parked in long-term parking at Philadelphia International Airport, 19% of the cars were white.  Which of the following statements is true?

• 19% and 23% are parameters, 100 is a statistic.
• 23% is a parameter, 19% is a statistic
• 23% is a statistic, 19% is a parameter
• 19%, 23%, and 100 are all statistics

The best statistic for estimating a parameter has which of the following characteristics?

• Low bias, high variability
• High bias, high variability
• Low bias.  Since a statistic should always equal the parameter it is estimating, there should be no variability
• Low bias, low variability

Which of the following best describes a sampling distribution?

• A probability distribution that describes the relative likelihood of all possible values of a statistic
• The distribution of all values of a statistic found in a large number of simulated samples of size n
• The set of all values of a variable in a large number of samples of size n
• The distribution of parameter values in all possible samples of size n

In a large population of adults, the mean IQ is 112 with a standard deviation of 20. Suppose 200adults are randomly selected for a market research campaign. The sampling distribution of thesample mean IQ is

• exactly Normal, mean 112, standard deviation 20
• approximately Normal, mean 112, standard deviation 0.1
• approximately Normal, mean 112, standard deviation 1.414
• exactly Normal, mean 112, standard deviation 1.414

Suppose you are sampling from a distribution that is strongly skewed left. Which of the following statements about the sampling distribution of the sample mean is true?

• As the sample size increases, the shape of the sampling distribution gets closer and closer to a Normal distribution
• As the sample size increases, the shape of the sampling distribution gets closer and closer to the shape of the population distribution
• As the sample size increases, the mean of the sampling distribution gets closer to the population mean
• Regardless of sample size, the shape of the sampling distribution is similar to the shape of the population distribution

In a study of the effects of acid rain, a random sample of 100 trees from a particular forest is

examined. Forty percent of these show some signs of damage. Which of the following statements

is correct?

• The sampling distribution of the sample proportion of damaged trees is approximately Normal.

• If we took another random sample of trees, we would find that 40% of these would show some

  signs of damage.

• If a sample of 1000 trees was examined, the variability of the sampling distribution of the sample proportion would be larger than in a sample of 100 trees.

• None of the above statements is correct.

Which of the following statements is/are true when taking an SRS from a large population?

I. The sampling distribution of x̄ has standard deviation σ/√n even if the population is not Normally distributed.

II. The sampling distribution of x̄ is Normal if the population has a Normal distribution.

III. When n is large, the sampling distribution of x̄ is approximately Normal even if the population is not Normally distributed.

• I and II

• I and III

• II and III

• I, II, and III

• I only

• II only

• III only

• I and III

• I, II and III