Replacement times for T.V. sets are normally distributed with a ...

[EAugust]

Replacement times for T.V. sets are normally distributed with a mean of 8.2 years and a standard deviation of 1.1 years (based on data from Getting Things Fixed, Consumers Reports). (a) Find the probability that a randomly selected T.V.
 
  will have a replacement time between 6.5 and 9.5 years. (b) Find the probability that a randomly selected T.V. will have a replacement time between 9.5 and 10.5 years. These two problems are solved almost exactly the same. Draw the diagram for each and discuss the part of the solution that would be different in finding the requested probabilities.

Question 2

Christine is currently taking college astronomy. The instructor often gives quizzes. On the past seven quizzes, Christine got the following scores:
 
  45 19 128 28 14 53 79
  Compute the standard deviation s.
  A) 40.1 B) 19,136.6 C) 128 D) 28,800

[djpooyouma]

Answer to Question 1

In part (a) and (b), the smaller area is subtracted from the larger area to get the requested probability.

Answer to Question 2

A

[EAugust]

TYSM

[xiaomengxian]

Excellent