Texas HS Mathematical Models Question of the Day
Test your knowledge with a hand-picked multiple-choice question.
An agricultural product company advertises to West Texas cotton growers: "Our fertilizer boosts yield by 15%." In field trials, 25 plots used standard practice (mean 780 lb/acre, sd 90) and 25 plots used the fertilizer (mean 870 lb/acre, sd 140).
Compute the percent change and test whether the difference is statistically significant at the 5% level using a two-mean $z$-test. Which evaluation is best?
Select an answer and click Check.