A school survey of 120 students records club membership and school lunch: 34 club members buy lunch, 21 club members bring lunch, 29 nonmembers buy lunch, and 36 nonmembers bring lunch. How many students buy school lunch?

A clinic records 75 patients: 50 got a flu shot, and 18 of those had a sore arm. Of the patients with no shot, 5 had a sore arm. How many got a shot with no sore arm?

A phone survey of 90 students records phone type and music streaming: 28 iPhone users stream, 17 iPhone users do not, 22 Android users stream, and 23 Android users do not. How many students stream music?

A class of 100 students is sorted by practice-app use and exam result: 36 used the app and passed, 14 used it and did not pass, 24 did not use it and passed, and 26 did not use it and did not pass. How many students used the app?

A bakery tracks 80 customers by coffee and tea orders: 19 ordered both, 31 ordered coffee only, 12 ordered tea only, and 18 ordered neither. How many customers ordered at least one of coffee or tea?

Of 60 students arriving at school, 40 biked and 20 walked. Among bikers, 22 wore helmets and 18 did not; among walkers, 12 wore helmets and 8 did not. What percent of the bikers wore helmets?

A factory checked 100 bottles by shift: morning made 45 acceptable and 5 defective bottles; evening made 30 acceptable and 20 defective bottles. What percent of the evening bottles were defective?

A pet survey has 24 dog owners in apartments, 16 dog owners in houses, 12 cat owners in apartments, and 28 cat owners in houses. To the nearest whole percent, what percent of apartment-pet owners have dogs?

A restaurant recorded 70 diners: lunch had 15 spicy orders and 25 mild orders; dinner had 18 spicy orders and 12 mild orders. To the nearest whole percent, what percent of diners who ordered spicy came for dinner?

A scatterplot shows 8 delivery routes, with distance in kilometers on the horizontal axis and driving time in minutes on the vertical axis. What description fits the relationship?

A scatterplot shows fertilizer in grams and seedling height in centimeters for 6 pots. What description best fits the plotted pattern?

A scatterplot shows battery age in months and charge capacity percent for 7 phone batteries. What description fits the relationship?

A scatterplot shows brightness setting and battery life in hours for 8 tablet tests. What description fits the relationship?

For 20 days at a snack stand, the reported correlation between temperature in °C and ice cream sales in dollars is $r=0.84$. What does this value say?

For 30 students, the correlation between absences and quiz score is $r=-0.18$. What does this value say about the linear relationship?

For 25 students, the correlation between shoe length in centimeters and reading score is $r=0.02$. What does this value suggest?

For 12 farms, the correlation between pesticide used in kilograms per hectare and insects per trap is $r=-0.76$. What does this value say?

A regression predicts quiz score in points from study time in hours: $\hat{y}=62+5.5x$. What score does the line predict for 4 hours?

A shower study predicts water used y in liters from time x in minutes: $\hat{y}=3.4+1.2x$. What does the line predict for an 8-minute shower?

A shop predicts a used bike's resale value y in dollars from age x in years: $\hat{y}=520-38x$. What value is predicted for a 6-year-old bike?

A farm model predicts chick weight gain y in grams from feed x in grams: $\hat{y}=7.5+0.35x$. What gain is predicted for 40 grams of feed?

For 18 commuters, a line predicts commute time y in minutes from distance x in kilometers: $\hat{y}=18+2.4x$. What does the slope mean?

For phones, $\hat{y}=35-0.6x$ predicts battery percent y after x minutes of video. What does the intercept mean?

For 40 students, $\hat{y}=72-1.8x$ predicts exam score y from missed classes x. What does the slope mean?

A tomato-height model used days 5 through 20 after sprouting: $\hat{y}=5.1+0.9x$, with y in centimeters. What is the best interpretation of the intercept?

An exam-score model used students who studied 1 to 8 hours: $\hat{y}=54+4.7x$. Why is the predicted score for 14 hours risky?

A plant model used temperatures from 10 °C to 28 °C: $\hat{y}=4.2+0.6x$. Is predicting growth at 22 °C interpolation or extrapolation?

A soda-sales model used spring school days with temperatures 15 °C to 28 °C: $\hat{y}=120+8x$. Why is a prediction for a 5 °C winter holiday weak?

A plant model predicts height y in centimeters from age x in weeks: $\hat{y}=12+3.5x$. A plant at 8 weeks was 42.5 cm tall. What is the residual?

A model predicts a test score from missed classes: $\hat{y}=95-6x$. A student who missed 7 classes scored 50. What is the residual?

A residual plot shows residuals for a linear model of reaction time in milliseconds from caffeine in milligrams. What does the pattern suggest?

A residual plot shows residuals for predicting delivery time in minutes from route distance in kilometers. What does the plot suggest?

For a regression of shipping cost in dollars on package mass in kilograms, $r^2=0.81$. What does this value mean?

For a regression of free-throw percentage on practice hours, $r^2=0.36$. What percent of variation in free-throw percentage is not accounted for by the model?

For a regression of used-car price on age, the reported correlation is $r=-0.70$. What is $r^2$?

Across beach towns, daily ice cream sales and water rescues have a strong positive correlation. Why does this not show that ice cream causes rescues?

In elementary students, shoe length in centimeters and vocabulary score have a positive correlation. What lurking variable could explain the association without bigger feet causing vocabulary growth?

A district finds schools with more classroom computers have higher exam averages. Why is a causal conclusion risky?

In data on town population and yearly library visits, 12 towns have 2,000 to 8,000 people and one city has 90,000 people. Why can the city be influential?

Nine runners trained 3 to 8 hours per week, and one runner trained 20 hours with a race time close to the fitted line through all points. What is likely if the 20-hour runner is removed?