Answer:
(1) Sample mean is 1480 hours and population standard deviation is 80 hours
(2) Null hypothesis: The mean lifetime of its fluorescent bulbs is 1500 hours
Alternate hypothesis: The mean lifetime of its fluorescent bulbs is less than 1500 hours
(3) 1.645
(4) D
(5) B
(6) A
Step-by-step explanation:
(1) From the population parameter, the sample mean is 1480 hours and population standard deviation is 80 hours
(2) The null hypothesis is statement deduced from the population parameter which is tested to be true or false
The alternate hypothesis is also a statement from the population parameter that negates the null hypothesis
(3) Using the standard normal distribution table, the critical value of one tailed test with significance level of 0.05 is 1.645
(4) Z = (sample mean - population mean)/(sd/√n)
sample mean = 1480, population mean = 1500, sd = 80, n = 40
Z = (1480 - 1500)/(80/√40) = -20/12.65 = -1.58
(5) The null hypothesis is rejected because the test statistic -1.58 is less than the critical value 1.645
(6) There is not enough evidence to support the claim that the mean lifetime of its fluorescent bulbs is 1500 hours because the null hypothesis is rejected
