Heat through the glass How well materials conduct heat matters when designing houses, for example.

Conductivity is measured in terms of watts of heat power transmitted per square meter of surface per degree Celsius of temperature difference on the two sides of the material. In these units, glass has conductivity about 1. The National Institute of Standards and Technology provides exact data on properties of materials. Here are measurements of the heat conductivity of 11 randomly selected pieces of a particular type of glass:22 1.11 1.07 1.11 1.07 1.12 1.08 1.08 1.18 1.18 1.18 1.12

(a) Is there convincing evidence that the mean conductivity of this type of glass is greater than 1?

(b) Given your conclusion in part (a), which kind of mistake—a Type I error or a Type II error—could you have made? Explain what this mistake would mean in context.