A poll reports a 95% confidence interval of 41% to 47% for the share of adults in a city who commute by bus. What does 95% describe?

A farm study gives a 90% confidence interval of 148 to 162 grams for the mean mass of its tomatoes. What does the 90% confidence level mean?

A school survey gives a 98% confidence interval of 0.62 to 0.70 for the proportion of students who support a later start time. What does 98% confidence refer to?

A clinic reports a 99% confidence interval of 12.4 to 15.8 minutes for the mean patient wait time. What does 99% confidence mean here?

A city survey gives an 80% confidence interval of 0.28 to 0.36 for the share of residents who bike to work. What is the meaning of 80% confidence?

In a random sample of 500 voters, p-hat = 0.58 favor a park plan. For a 95% confidence interval with z* = 1.96, what is the margin of error, rounded to three decimals?

A random sample of 36 backpacks has x-bar = 2.06 kg, s = 0.26 kg, and t* = 2.030. What is the 95% margin of error, rounded to 0.01 kg?

A 95% confidence interval for a population mean uses a sample of 64 people. If the sample size becomes 256 and the sample variability and confidence level stay the same, what happens to the margin of error?

In a random sample of 250 tablets, 100 passed a battery test, so p-hat = 0.40. For a 90% confidence interval with z* = 1.645, what is the margin of error to three decimals?

A 95% confidence interval for the mean daily water use in a dorm is 18.6 to 21.4 liters. What is the margin of error?

A 95% confidence interval for a population proportion is built from p-hat = 0.52 with margin of error 0.06. If the confidence level rises to 99% with the same data, what happens to the margin of error?

A random sample of 60 machine parts finds 3 defective parts. A one-sample z interval for the defective proportion is planned. What condition is not met?

A researcher wants a one-sample t interval for mean commute time from 16 randomly chosen workers. The histogram shows their commute times. What condition is in doubt?

A website asks visitors to click a survey about a city recycling rule, and the first 200 volunteers respond. The city wants a confidence interval for all residents. What condition is most clearly violated?

A school randomly samples 80 students from 900 and finds p-hat = 0.30 favor a new schedule. What condition is supported by the 10% check?

A researcher randomly samples 40 corn plants from a large field. Their heights have a roughly symmetric distribution with no outliers. What supports using a one-sample t interval for mean height?

A 95% confidence interval for the mean commute time of workers in a town is 24.1 to 29.3 minutes. What population mean is supported as plausible?

A 95% confidence interval for the share of households that recycle is 0.48 to 0.56. A mayor claims the population share is 0.60. What does the interval support?

A 90% confidence interval for the mean daily water use of homes is 46 to 54 liters. What does the interval say about a population mean of 50 liters?

A factory reports a 95% confidence interval of 0.12 to 0.18 for the proportion of tablets with a cosmetic defect. What is the best interpretation?

A 99% confidence interval for the mean mass of cereal boxes is 498.2 to 501.6 grams. The label target is 500 grams. What does the interval say?

A 95% confidence interval for the mean increase in greenhouse temperature during a test is 1.2 to 3.8 °C. What conclusion is supported?

A random sample of 120 students answers yes or no about buying school lunch. The goal is to estimate the schoolwide yes proportion. Name the confidence interval procedure.

A bottling company randomly chooses 18 water bottles and records fill volume in milliliters. It has x-bar and s and wants the mean fill volume. Name the confidence interval procedure.

Two independent random samples of bean plants receive fertilizer A or fertilizer B. Researchers record growth in centimeters and want the difference in population mean growth. Name the confidence interval procedure.

The same 20 athletes have sprint times measured before and after a training plan. The coach wants the mean change in time. Name the confidence interval procedure.

In a random sample of 400 shoppers, 140 used a loyalty card, so p-hat = 0.35. With z* = 1.96, what is the 95% confidence interval for the population proportion?

A random sample of 250 residents finds 90 support a new park, so p-hat = 0.36. With z* = 1.645, what is the 90% confidence interval for the support proportion?

A random survey of 1000 adults finds 620 favor adding bus lanes, so p-hat = 0.620. With z* = 1.96, what is the 95% confidence interval for the population proportion?

A random sample of 600 bulbs finds 168 last at least 900 hours, so p-hat = 0.28. With z* = 2.576, what is the 99% confidence interval?

A random sample of 150 packages finds 45 have a label error, so p-hat = 0.30. With z* = 1.96, what is the 95% confidence interval for the error proportion?

A random sample of 320 app users finds 208 enabled notifications, so p-hat = 0.65. With z* = 1.96, what is the 95% confidence interval for the population proportion?

A random sample of 25 batteries has x-bar = 41.2 hours, s = 3.0 hours, and t* = 2.064. What is the 95% confidence interval for the population mean life?

A random sample of 16 seedlings has x-bar = 82.0 cm, s = 4.8 cm, and t* = 2.131. What is the 95% confidence interval for the population mean height?

A random sample of 49 water meters has x-bar = 6.8 liters, s = 1.4 liters, and t* = 2.010. What is the 95% confidence interval for the population mean reading?

A random sample of 36 students has x-bar = 14.5 minutes of daily exercise, s = 6.0 minutes, and t* = 2.030. What is the 95% confidence interval for the population mean?

A random sample of 10 soil plots has x-bar = 23.4 grams of nitrogen, s = 2.5 grams, and t* = 2.262. What is the 95% confidence interval for the population mean?

A pollster wants margin of error 0.03 at 95% confidence for a population proportion, using p-hat = 0.5 and z* = 1.96. What sample size is needed?

A survey planner wants margin of error 0.04 at 90% confidence for a population proportion, using p-hat = 0.5 and z* = 1.645. What sample size is needed?

An inspector wants margin of error 2 grams at 95% confidence for mean package mass, using estimated sigma = 12 grams and z* = 1.96. What sample size is needed?