Many customers complain because the declared lifetime of the light bulb you produce is 1000 hours, while they seem to break much faster. You want to test whether this is true or not, in order to improve your service, The results for the lifetime, in hours, for a sample of 30 light bulbs is X=970 S=20
a. state the null hypothesis
b. State the test you will use(one or two tails,Z or t)
c. Decide the level of significance (?r the confidence level)
d. find the region of non rejection for your variable (or the region of rejection)
e. Find the value of your variable
f. decide if your null hypothesis is rejected or not
g. If we assume the proportion does not change what should be the sample size in order to reject the null hypothesis (in case it were not rejected)?