A factory that manufactures screws is performing a quality control experiment. Each object should have a length of no more than 18 centimeters. The factory believes that the length of the screws is...

A factory that manufactures screws is performing a quality control experiment. Each object should have a length of no more than 18 centimeters. The factory believes that the length of the screws is less than this value and measures the length of 86 screws. The sample mean screw length was 17.94 centimeters. The population standard deviation is known to be σ=0.24 centimeters.

What is the null hypothesis?

What is the alternative hypothesis?