TV safety The manufacturer of a metal stand for home TV sets must be sure that its product will not fail under the weight of the TV. Since some larger sets weigh nearly 300 pounds, the companys safety inspectors have set a standard of ensuring that the stands can support an average of over 500 pounds. Their inspectors regularly subject a random sample of the stands to increasing weight until they fail. They test the hypothesis H0: m = 500 against HA: m 7 500, using the level of significance a = 0.01. If the sample of stands fails to pass this safety test, the inspectors will not certify the product for sale to the general public. a) Is this an upper-tail or lower-tail test? In the context of the problem, why do you think this is important? b) Explain what will happen if the inspectors commit a Type I error. c) Explain what will happen if the inspectors commit a Type II error.

Ch. 4 Probability • Statistics: the science of decision-making in the face of uncertainty • Probability: a numerical measure of the likelihood that an outcome or an event occurs • Probability of an event A = P(A) • Requirements for Probability of Discrete Variables: o 0 <= P(A) <= 1 o When P(A) = 0, it is an impossible event o When P(A) = 1 it is a certain event o The sum of the probabilities of all possible outcomes must equal 1 (100%) • Conditional Probability: the chance that one event happens, given that another event has happened/will occur o P(A|B) = probability of event A given thatB has occurred o P(A|B) = (P(A +B))/(P(B)) • General Rules: o P(A+B) = P(A) x P(B|A) o P(A or B) =