3.1 Practice: Intro to Confidence Intervals

A confidence interval is...

• created to estimate sample means or proportions

• created to estimate a true parameter (mean or proportion) of a population

• a single value that estimates a parameter

• not an appropriate way to estimate a mean

The symbol for the sample proportion is __________.

• x̄

• p̂
• E
• q

Which of the following is the definition of a "point estimate?"

• The average of a population.

• The average of a sample.

• The midpoint of a confidence interval.

• The confidence interval.

A random sample of 100 WHS students found that 53 of them were in possession of a pencil. What is the p-hat for this sample?

• 0.53

• 0.5

• 0.47

• 1

The amount added and subtracted to the point estimator.

• Margin of Error

• Point Estimator

• Statistic

• Population

If the 95% Confidence Interval for a population mean is (114.56, 125.54), then is it likely that the true population mean µ is greater than 130?

• Yes

• No

• Not enough information

In a survey of 104 students, it was found that 79 went to the homecoming game this year.

A 99% confidence interval for p is (0.652, 0.868). Interpret this interval.

• 99% of the time the true proportion of people who went to the homecoming game this year is between 65.2% and 86.6%.

• The probability that the population proportion of people who went to the homecoming game this year is between 65.2% and 86.6% is 95%.

• We are 99% confident that the true proportion of people who went to the homecoming game this year is between 65.2% and 86.6%.

• 99% of all possible intervals calculated this way will capture the true proportion of people who went to the homecoming game this year

A gaming website wanted to find out which console its visitors owned.
Which choice best represents the population?

• Visitors to the 3DS section.
• All of the website visitors.
• Visitors to the PS4 section.
• Visitors who are on the website for more than 5 minutes.

As part of a 6th grade statistics project, the teacher brings a candy jar full of gumballs (red & green). The assignment is to estimate the proportion of red gumballs in the jar. Suppose one of the students draws 25 gumballs from the jar: 8 are red, 17 are green. What is the SAMPLE?

• 25 gumballs drawn
• all gumballs in the jar
• the students
• the 17 green gumballs

The symbol for the population proportion is __________.

• Z

• p̂
• P

• n