(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. Defining and using appropriate notation, state the null and alternative hypotheses of this test. (e) Use Minitab to perform the appropriate I-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. [3] [2] [6] (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. [4]