Question 3

(a) A researcher reports that the average annual salary of a CEO is more than RM42,000. A sample of 30 CEOs has a mean salary of RM43,260. The standard deviation of the population is RM5,230. Using = 0.05, test the validity of this report. (4 marks)

(b) A researcher wants to test the claim that the average lifespan time for fluorescent lights is 1,600 hours. A random sample of 100 fluorescent lights has mean lifespan 1,580 hours and standard deviation 100 hours. Is there evidence to support the claim at = 0.05? (4 marks)

(c) The Human Resource Department claims that the average entry point salary for graduate executive with little working experience is RM24,000 per year. A random sample of 10 young executives has been selected, and their mean salary is RM23,450 and standard deviation RM400. Test this claim at 5% level. (4 marks)

(d) A researcher wants to conclude whether the average annual income of families in a residential area exceeds RM14,000. A random sample of 60 families has been selected. The sample gives average annual income of RM14,100 with standard deviation RM400. At 5% level, make a statistical test to help the researcher make the above conclusion. (4 marks)