Answer Happy

5. (a) In order to compare the percentage of revenue spent on R&D between companies of industrial sectors A and B, random samples of companies are drawn with summary provided below: Industrial Sector Sample Size Mean Standard Deviaton A 15 8.5% 2% B 16 10% 2.1% Is there any evidence indicating that the mean percentage of revenue spent on R&D for companies of sector A is less than that of sector B at 5% level of significance? State your assumptions. (7 marks) Answer Video (b) A market research analyst has studied the preference of customers for four competitive brands of cars, namely A, B, C and D, for many years. In the last year, the percentages of customers preferring Brand A, B, C and D were 15%, 25%, 40% and 20%, respectively. In this year's study, the number of customers that prefer each of the four specific brands are tabulated below: Brand A B С D Number of customers 14 42 106 38 Test whether customer preference is changed in this year at 1% level of significance. (6 marks) Answer Video (c) The staff association of a company wants to investigate the association between employee's years of service and level of satisfaction on the remuneration package provided by the company, the results of a random sample of employees are summarized below: Level of satisfaction Years of service Unsatisfactory Neutral Satisfactory 9 < 5 years 29 72 5 - <10 years 68 46 30 10 - < 15 years 40 57 49 Test whether the employee's years of service and the level of satisfaction on the remuneration package are independent at 1% level (7 marks) of significance.