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(a) In one or two sentences, describe how your experiment went; for example, mention any difculties that you faced along the way. Then present a table of your collected data, similar in layout to Table 3 of Unit 10 (Subsection 3.4). Indicate clearly the units in which you made your measurements [for example, millimetres] and the measurements that correspond to seedlings whose stems were cut during their growth. Then proceed to part (b) of the question. If, however, you were unable to collect data of your own, then state this and explain why. Instead of presenting results in a table, draw stemplots for each of the two samples of data given in Table 1, including only measurements from seedlings whose stems were cut during growth. Also, give the main reason for producing such sternplots in the context of a ttest, and comment on the shape of the stemplots relative to this reason. Table l Lengths of roots (in mm) obtained in a mustard seedlings experiment Seedlings grown in light Seedlings grown in dark 24 29 26 x x 25 32 x 22 42 X 28 22 30 19 42 37 33 19 X x 44 x 37 31 X 26 28 x 33 27 28 21 29 18 30 x 27 29 30 In Table 1, measurements given in bold were obtained from seedlings whose stems were cut during their growth. A cross indicates a seed which did not germinate. To answer the remainder of this question, you should use your own data if you have them. Otherwise, use the data from Table 1. (b) (C) (d) (1') Run Minitab and type your data. into columns headed Light, for lengths of roots of seedlings grown in light, and Dar]:1 for lengths of roots of seedlings grown in the dark, for all the seedlings whose stems you cut. In your answer, provide a. list of the data as it appears in your Minitab worksheet. (You should also save a copy of your worksheet in order to be able to work on it again at another time.) Use Minitab to calculate the values of the sample variances of the two columns of data. Include a copy of the relevant Minitab output in your answer. page 3 of6 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. 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. Use Minitab to perform the appropriate t-test on your data. (You should assume that the assumption of a common population variance is reasonable, regardless of the outcome 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. A reservation about your conclusions in part (c), 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
