Estimating the Difference between Two Population Proportions — Unit test Answers

In a statistics activity, students are asked to determine if there is a difference in the proportion of times that a spinning penny will land with tails up, and the proportion of times a spinning dime will land tails up. The students are instructed to spin the penny and the dime 30 times and record the number of times they land tails up. For one student, the penny lands tails side up 18 times, and the dime lands tails side up 20 times. Assuming the conditions for inference are met, what is the 98% confidence interval for the difference in proportions of tails side up for a penny and a dime?Find the z-table here.

A researcher takes a random sample of 2,496 drivers and finds that 1,603 put their phone in "drive mode” to not be distracted while driving. A 90% confidence interval for the proportion of drivers who use "drive mode” on their phones is (0.626, 0.658). Which statement correctly interprets the interval?

A local school board wants to determine the proportion of households in the district that would support starting the school year a week earlier. They ask a random sample of 100 households whether they would support starting the school year a week earlier, and 43 households responded that they would. The school board plans to construct a 95% confidence interval for the true proportion of households that would support starting the school year a week earlier. Are the conditions for inference met?

A computer company wants to determine the proportion of defective computer chips from a day’s production. A quality control specialist takes a sample of 100 chips from the first hour of production and determines that there are 12 defective chips. He wants to construct a 90% confidence interval for the true proportion of defective chips from a day’s production. Are the conditions for inference met?

In a small town of 5,832 people, the mayor wants to determine the proportion of voters who would support an increase to the food tax. An assistant to the mayor surveys 500 randomly chosen people, and finds that 240 support the increase. Assuming the conditions for inference have been met, what is the 95% confidence interval for the true proportion of people who would support the increase in food tax?