Testing a Claim about a Mean

A company that produces steel ingots has always made their ingots with a mean of 20 inches long. However, the plant manager is increasingly concerned that the machines might be producing the ingot too small.

To test this thought, he takes a random sample of 10 ingots. The lengths of those ingots are below.

19.9, 19.8, 19.81, 19.85, 19.94, 20.01, 20.02, 19.93, 19.86, 19.92