3. QUALITY CONTROL A worker at an automobile assembly plant checks new cars for defects. Of the first 280 cars he checks, 4 have defects. If 10,500 cars will be checked this month, predict the total number of cars that will have defects.

To predict the total number of defective cars this month, we can start by calculating the defect rate based on the initial sample. Out of 280 cars, 4 were defective, giving a defect rate of 4/280, which simplifies to about 0.0143, or 1.43%. To find out the expected number of defective cars in the full sample of 10,500 cars, multiply 10,500 by 0.0143. Doing so gives us approximately 150 defective cars expected this month. To put it in a fun context, imagine a big car parade of shiny new vehicles zooming down the street! With our prediction, if those 10,500 cars were stars, around 150 of them would be wearing "I have a defect" badges as they roll along. So, while the majority will shine bright and problem-free, it’s always good to keep an eye out for those few that need a little extra TLC!