Forever Power Company analysts conducted tests on the life of its batteries and those of a competitor (Brand X). They found that their batteries had a mean life (in hours) of 26.6, with a standard deviation of 4.3. Their results for a sample of 10 Brand X batteries were as follows: 13, 17, 20, 24, 26, 26, 29, 32, 34, 37.
a. Find the mean and standard deviation for the sample of Brand X batteries.
b. Which batteries have a more uniform life in hours?
c. Which batteries have the highest average life in hours?

Asays "we are both knaves" and b says nothing. exercises 24–31 relate to inhabitants of an island on which there are three kinds of people: knights who always tell the truth, knaves who always lie, and spies (called normals by smullyan [sm78]) who can either lie or tell the truth. you encounter three people, a, b, and c. you know one of these people is a knight, one is a knave, and one is a spy. each of the three people knows the type of person each of other two is. for each of these situations, if possible, determine whether there is a unique solution and determine who the knave, knight, and spy are. when there is no unique solution, list all possible solutions or state that there are no solutions. 24. a says "c is the knave," b says, "a is the knight," and c says "i am the spy."