Q1.

BIG Corporation advertises that its light bulbs have a mean lifetime, ?, of 2900 hours. Suppose we have good reason to believe that ? is less than 2900 hours and decide to do a statistical test of the claim. We choose a random sample of light bulbs manufactured by BIG and find that the mean lifetime for this sample is 2740

hours and that the sample standard deviation of the lifetimes is 650 hours.

Based on this information, complete the parts below.

(a)	What are the null hypothesis H0 and the alternative hypothesis H1 that should be used for the test?
H0:
H1:
(b)	Suppose that we decide to reject the null hypothesis. What sort of error might we be making?
	?(Choose one) Type 1, Type 2
(c)	Suppose the true mean lifetime of BIG's light bulbs is 2900 hours. Fill in the blanks to describe a Type I error.
A Type I error would be ?(Choose one- rejecting, failing to reject) the hypothesis that ? is ?(Choose one- less than, less than or equal to, greater than, greater than or equal to, not equal to, equal to) ?(Choose one- 2740, 2900, 650) when, in fact, ? is ?(Choose one- equal to 650, equal to 2900, less than 650, less than 2740, less than 2900, greater than 2900) .

Q2.

An independent consumer group published its finding that the lifetimes of electric bulbs manufactured by BIG Corporation are approximately normally distributed with a mean of 640 days and a standard deviation of 121. BIG Corporation claims that the standard deviation of its electric bulbs is less than 121. Suppose that we want to carry out a hypothesis test to see if BIG Corporation's claim is correct. State the null hypothesis , and the alternative hypothesis , that we would use for this test. H : 0 X P H : 0 P O S OSO >0 020 0=0 0#0 X 5