9. The next year there is a new head gardener who decides to run the same experiment but over 2 different years, differently from 8. Let's assume that these 2 years have remarkably similar weather so the plants will behave the same each time except for the effects of the fertiliser. The gardener compares the growth rate of each individual plant between the 2 gardening seasons. The average difference in monthly growth rate (inches) for the plants is 1.55 with a standard deviation of 0.093. They choose only 49 plants for this experiment. (a) Construct a 95% confidence interval for the difference between the average growth rate of the plants between the 2 gardening seasons. (b) Which of the two 95% intervals (the one from question 8a or from this question part a) is narrower? Why is it so? (c) Which of the two 95% intervals (the one from question 8a or from this question part a) is more convincing in making a point that the head gardener should start using the newer fertiliser, if there is a difference?