A report shows that Covid-19 reduced household expenditure in Europe by 8% in 2020. Elsewhere, consumer spending also dropped significantly in 2020, with 4% seen in the United States, and 17% reported in China (Broom, 2021). After reading the report, Mr. Goh, a student of Singapore University of Social Sciences, was interested to find out how Covid-19 has affected the household spending in Singapore. Surprisingly, he found news saying that consumer spending among Singapore residents was resilient and at a similar level to 2019 (Choo, 2021). In order to have a better understanding of the impact of Covid-19 on household spending of Singapore residents, Mr. Goh decided to conduct a survey. He got a random sample of 32 students from Singapore University of Social Sciences, and collected data on their average monthly household expenditure in 2019 and 2020. Based on his own experience, he hypothesised that the household expenditure of Singapore residents in 2020 is lower than that in 2019. The data is given in the Excel data file "BUS105_household expenditure":

Average Monthly Household Expenditure (SG$) Household No. Year 2019 Year 2020 1 3100 3720 2 8250 5940 3 5430 5919 4 5900 5723 5 3900 3198 6 6300 7560 7 4800 5760 8 7400 6734 9 9210 8197 10 5950 6962 11 4390 3249 12 5520 3919 13 5810 4648 14 6360 5724 15 6490 7528 16 4290 3947 17 5550 4329 18 8280 8528 19 7360 6330 20 7810 6170 21 6745 7082 22 5630 4335 23 6530 4571 24 4570 5301 25 5790 6832 26 6390 6710 27 5210 4741 28 3670 2789 29 4420 4243 30 4690 5065 31 5630 5461 32 5910 4373

Question 1 (a) Describe 99% confidence interval of the mean monthly household expenditure in 2019 and 2020, respectively. Interpret and discuss whether Mr. Goh can conclude that the household expenditure of Singapore residents in 2020 is lower than that in 2019. (20 marks) (b) Apply an appropriate hypothesis test to determine if the household expenditure of Singapore residents in 2020 is lower than that in 2019, at the significance level of 1%. Examine the assumptions required to perform the test. Are these assumptions reasonable? Please provide explanations. (30 marks) (c) Criticise the analysis done by Mr. Goh by identifying three (3) concerns. If you have a free hand to study this research question starting from data collection to analysis, explain how you would conduct the project. Keep your answer within 3oo words and indicate your word count at the end of your answer. (30 marks)

(d) Summarise the above analysis in a simplified report. You may also use the result you have developed in your TMA. The word limit is 3oo words. Please indicate the word count at the end of your answer. (20 marks)