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page 3 of 5 IS study soume was downloaded by IWM'BSAITOTS from CourseHermmm on 08102022 [0:57:41 GMT DS:00 isal'fwwrourseheracomtle' l3ST624Tf22m l4una04-bpd" (c) Using the information you obtained in part (b), check whether it is reasonable to assume that the two samples come from populations whose distributions have a common variance. (d) To investigate whether light affects root growth (when stems have been cut during growth), a t-test is to be performed on the measurements that you made. Dening and using appropriate notation, state the null and alternative hypotheses of this test. (e) Use Minitab to perform the appropriate ttest on your data. (You should assume that the assumption of a common population variance is reasonable, regardless of the outoome of your investigation in part (c).) Include a copy of the entire Minitab output of the test in your answer. What is the result of the t-test? Carefully report your conclusions concerning the question of whether light affects root growth of mustard seedlings. (f) A reservation about your conclusions in part (e), given the way in which the experiment was designed and carried out, might be that cutting the stems could have different effects in the light and in the dark. Give two other valid reservations. Question 2 (Unit 10) 9 marks Do not use Minitab to answer this question. Do the calculations 'by hand' (using a calculator), showing your working. A guidebook claims that their suggested Walk A takes 45 minutes to complete. In order to test this claim, 18 people use the guidebook to follow the suggested route. They recorded how long, in minutes, it took each person to complete the walk. The walkers do not walk together in a group, but each walker completes the walk by themself. The results are summarised in Table 2. Table 2 Summary statistics for the time (in minutes) taken to complete Walk A by each walker Walk number sample size mean standard deviation Walk A 18 38 7 (a) What is the most appropriate version of the tteet if you want to test the null hypothesis that the underlying population mean time taken to complete the walk is what the guidebook claims it to be and the alternative hypothesis that the underlying population mean time is not what the guide claims? Justify your choice. (b) What are the number of degrees of freedom and the 5% critical value for the most appropriate t-test applied to these data? (c) Without using Minitab, calculate a 95% condence interval for the population mean time taken to complete this walk. Your answer should be rounded to one decimal place. (d) Based on your calculated 95% condence interval, is it plausible that the underlying population mean time taken to complete the walk is 45 minutes as claimed by the guidebook? Justify your answer. page 4 of 5 is sludv sum was downloaded bv IWM'JMTOTS from CeurseHerrmm-n on (18le2022 10:57:41 GMT DS:00 [3] [2] [0']