Prob and Stats Exam Review

You guess on every answer of a 3 question multiple-choice test. Each question has 5 possible answers. What is the probability you get only 1 of the questions right?

• 38.4%

• 2.4%

• 51.2%

• 61.6%

The amount that households pay service providers for access to the Internet varies, with a mean monthly fee of $48 and standard deviation of $20. The distribution is not normal. A sample survey asks a SRS of 500 households with Internet access how much they pay per month. Let X-bar be the mean amount paid by the members of the sample. What is the shape of the sampling distribution of x-bar?

• Approximately Normal, since Large Counts is met.

• Approximately Normal, since Central Limit Theorem is met.

• Not Approximately Normal, since Large Counts is NOT met.

• Not approximately Normal, since Central Limit Theorem is NOT met.

These symbols represent the mean and standard deviation for which of the following distributions?

• The Population

• The Sample

• The Sampling Distribution

These symbols represent the mean and standard deviation for which of the following distributions?

• The Population

• The Sample

• The Sampling Distribution

A study of voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election. Election records show that only 56% of registered voters voted in the election. Which of the following statements is true about these percentages?

• 72% and 56% are both statistics

• 72% is a statistic and 56% is a parameter

• 72% is a parameter and 56% is a statistic

• 72% and 56% are both parameters

A state trooper randomly selects 50 cars driving on the freeway, records the state identified on the license plate, and calculates the proportion of cars with out-of-state plates. Which of the following describes the sampling distribution of the sample proportion in this context?

• The distribution of state for all cars in the troopers sample of cars on the freeway

• The distribution of state for all cars passing on this freeway

• The distribution of the proportion of cars with out-of-state plates in all possible samples of 50 cars on this freeway

• The distribution of the proportion of cars with out-of-state plates in the trooper's sample of 50 cars on this freeway

At a high school, 85% of students are right-handed. Let X = the number of students who are right-handed in a random sample of 10 students from the school. Which of the following statements about the mean and standard deviation of the sampling distribution of X is true?

• Neither the mean or the standard deviation can be determined from the information given

The student newspaper at a large university asks an SRS of 250 undergraduates, "Do you favor eliminating the carnival from the end-of-term celebration?" In this sample, 150 of the 250 undergraduates are in favor. Suppose that 55% of all undergraduates favor eliminating the carnival. If you took a very large number of SRSs of size n = 250 from this population, the sampling distribution of the sample proportion would have which of the following characteristics?

• Mean = 0.55; standard deviation = 0.03; shape unknown

• Mean = 0.55; standard deviation = 0.03; shape approximately Normal

• Mean = 0.60; standard deviation = 0.03; shape unknown

• Mean = 0.60; standard deviation = 0.03; shape approximately Normal

Scores on the SAT math exam followed a normal distribution with mean 515 and standard deviation 114. You choose a SRS of 100 students and calculate a mean math score. Which of the following are the mean and standard deviation of the sampling distribution of the sample means?

• Mean = 515; SD = 114

In a congressional district, 55% of the registered voters are Democrats. Which of the following is closest to the probability of getting less than 50% Democrats in a random sample of size 100?

• 0.157

• 0.496

• 0.504

• 0.843