Exam 2 Review

The Indianapolis Star conducts a poll of Indiana residents to see how many approve of the governor's performance. They ask 1000 randomly chosen adults. When the Star publishes the results, the article says that the governor's approval percentage among the Indiana adults is 42.7% +/- 3.12%, with 95% confidence. This means that

• There is a 95% chance that the percentage of Indiana adults who approve of the governor is between 39.62% and 45.82%.

• 95% of the time, the percentage of Indiana adults who approve of the governor is between 39.62% and 45.82%.

• We can be 95% confident that the number of people in the sample who said they approve of the governor is between 396 and 458.

• 95% of the time, the confidence interval constructed will contain the percentage of Indiana adults who approve of the governor.

The histogram which shows all possible averages for the draws from a box and their probabilities is

• the population parameter, the average of the box.

• the expected value for the average of the draws.

• a confidence interval for the average of the box.

• the margin of error.

• the probability histogram for the average of the draws.

"Congress has passed a ban on the sale of assault weapons. Now there is a move to repeal that ban. Do you agree that the ban on sale of assault weapons should be repealed?" You ask that to a SRS of 1000 adults in Texas and to a seperate SRS of 1000 adults in Indiana.

You make 95% confidence interval statements about the percents of all adults in both stats who agree. Your margin of error for Indiana is

• the same as in Texas, because the two SRS's are the same size.

• larger than in Texas, because there are fewer people in Indiana.

• smaller than in Texas, because there are fewer people in Indiana.

• may be either smaller or larger than in Texas, because the sample result varies due to chance.

• smaller, because everything is bigger in Texas.

This opinion poll described previously refers to repealing the ban on the sale of assault weapons. It would be cheaper to just announce the question on TV in these states and ask people to call in with their opinions. Is this a good or bad idea, and why?

• This is a good way to get information on the opinions of adults.

• This is a bad idea because if only a few peoppe call in your margin of error will be large.

• This is a bad idea because allowing people to volunteer may result in large bias.

• This is a bad idea because there is no control group.

• This is a bad idea because the study isn't double blind.

Another question posed of the Texans was "what age should a person be allowed to purchase a gun?" The average of the 1000 surveyed was 18.8 years and an SD of 1.2 years. Find a 95% confidence interval for the average age.

• 18.72 to 18.88 years

• 17.6 to 20 years

• 18.76 to 18.84 years

• 18.8 to 19.2 years

Select all of the requirements for a confidence interval to be accurately calculated.

• SRS

• Large sample size

• Histogram of the tickets in the box must look approximately normal

The probability of an outcome of a random phenomenon is

• another name for its expected value.

• the confidence level.

• either 0 or 1, depending on whether or not the phenomenon can actually occur.

• the percentage of times an outcome is likely to occur in a very long series of repetitions.

Suppose we draw 5 cards without replacement. The probability your card is the ace of diamonds given the first 4 cards were hearts is

• 1/48

• 4/48

• 4/52

• 1/52

• 12/52 x 11/51 x 10/50 x 9/49 x 1/48

Suppose I draw a card from a well shuffled deck, and I roll a fair, 6-sided die; then I toss a fair coin. The probability the card is spades, an odd number is rolled, and the coin is tails is

• Events are dependent

• Not mutually exclusive, cannot compute

• 1/4 x 1/2 x 1/2

• 1/4 + 1/2 + 1/2

Suppose I draw 3 cards with replacement from a well shuffled deck. What is the probability that I get at least one ace?

• 469/2197

• 3/13

• 2196/2197

• 1/2197