Expo dry-erase markers are typically considered some of the best in the industry for their clarity and lifespan. A major competitor named Whypo claims that their markers last longer on average than Expo markers and they attempt to show this fact by using a random group of 15 Whypo markers. Whypo finds that their markers have a mean lifespan of 32 days, with a standard deviation of 8 days. Typically, an Expo marker under daily use will have a lifespan of 20 days before needing to be replaced

Check the conditions for Whypo's Hypothesis