A bakery weighs a random sample of 28 loaves and tests whether the mean mass differs from the labeled 500 grams; the population sigma is unknown. Which procedure is needed?

A school surveys 180 randomly chosen students and tests whether more than 60% prefer online homework. Which procedure matches this question?

A clinic records the resting pulse rates of 35 adult patients and tests whether the mean pulse rate is below 72 beats per minute; sigma is unknown. Select the procedure.

A city samples 420 drivers and tests whether the proportion who wear seat belts is different from 0.90. What inference procedure applies?

A factory samples 40 filled bottles and tests whether the mean volume is less than 250 milliliters; sigma is not known. Which test should be used?

A poll of 250 voters tests whether the proportion supporting a school bond is greater than 50%. Which procedure fits the data and question?

A farm randomly samples 22 tomato plants and tests whether the mean yield is above 3 kilograms per plant; sigma is unknown. Identify the procedure.

An online store samples 600 orders and tests whether fewer than 8% are returned. Which inference procedure is appropriate?

A researcher samples 16 aquarium tanks and tests whether the mean nitrate level differs from 20 milligrams per liter; sigma is unknown. Which procedure is called for?

A library samples 300 cardholders and tests whether the proportion who used an e-book last month is greater than 0.35. Which test is right?

Thirty students take a typing test before and after a keyboarding course, and the teacher tests whether mean speed changed. Which procedure should analyze the results?

A nutritionist compares mean daily sodium intake for 45 randomly selected athletes and 50 randomly selected nonathletes. Which procedure fits this comparison?

A lab measures the same 18 water samples with an old meter and a new meter, then tests whether mean readings differ. Choose the procedure.

A district wants to test whether the mean commute time differs from 25 minutes using one random sample of 52 teachers. What procedure is appropriate?

A coach randomly assigns 20 cyclists to training plan A and 22 others to plan B, then compares mean race times. Which procedure is needed?

A doctor records each patient's blood pressure before and after a medication and tests whether the mean change is negative. Which procedure applies?

A forester measures tree heights in one random sample of 34 maple trees and tests whether the mean height is 12 meters. Which procedure fits?

A hospital compares mean recovery time for 36 surgery patients and 40 physical-therapy patients, with different people in each group. Which procedure is appropriate?

A university wants a range of plausible values for the mean number of hours students study per week, using a random sample of 80 students. Which procedure fits the goal?

A county health office asks whether the proportion of residents who got a flu shot is below last year's 48%. What procedure matches that goal?

A museum wants to estimate the proportion of visitors who buy a guidebook, with a margin of error, from a random sample of visitors. Which procedure should it use?

A delivery company asks whether its mean package arrival time is less than 2.5 days, using a random sample of 70 arrivals. Which procedure is called for?

A principal wants to report an interval estimating the proportion of students who ride the bus to school, based on a random sample of 240 students. Select the procedure.

A conservation group samples 50 seedlings to test whether the mean growth after 30 days differs from 8 centimeters. Which procedure fits the research question?

A cereal maker claims the colors in its bags follow 40% brown, 30% yellow, 20% red, and 10% orange. One random bag is counted. Which procedure tests this claim?

A researcher records gender and preferred study location for 300 college students in one random sample and asks whether the variables are associated. Which test applies?

Three hospitals each sample patients and record whether the discharge rating is excellent, good, fair, or poor, then compare the rating distributions. Which procedure is appropriate?

A die manufacturer rolls one die 600 times and tests whether the six face outcomes occur equally often. Which procedure should be used?

A survey of 500 adults records age group and favorite news source and tests whether the two classifications are related. Which procedure fits?

A teacher samples freshmen, sophomores, juniors, and seniors separately and compares the distribution of favorite math topic across grades. Which procedure is needed?

A botanist counts flower colors from one random sample of 200 plants to test a genetic model predicting a 9:3:3:1 color ratio. Which procedure applies?

A company records department and commute method for one sample of employees, then tests whether commute method depends on department. Which procedure is appropriate?

A clinic compares a new reminder text with no reminder by randomly assigning 200 patients to each group and testing whether the proportions attending appointments differ. Which procedure fits?

A scientist compares mean dissolved oxygen levels in 25 river sites upstream and 25 different sites downstream. Which procedure should be used?

Two ads are shown to separate random groups of 150 shoppers each, and analysts test whether click-through proportions differ. Select the correct procedure.

A researcher compares average sleep hours for 60 randomly chosen night-shift nurses and 55 randomly chosen day-shift nurses. Which procedure matches the data?

A school compares the proportions of 9th graders and 12th graders who passed a driving-knowledge quiz, using separate random samples. Which test is appropriate?

A farm compares mean milk production, in liters per day, for 32 cows on feed A and 30 different cows on feed B. Which procedure is needed?

A website tests whether the proportion of mobile users who complete checkout differs from the proportion of desktop users who complete checkout. Which procedure applies?

An engineer compares mean battery life for 40 phones using chip X and 42 different phones using chip Y. Which test should analyze the results?