(i) Estimate, by eye, the mean of the normal distribution given in Figure 8.4.

(ii) Estimate the standard deviation by using the fact there are approximately three standard deviations between the centre and each extreme tail.

(iii) Estimate the standard deviation by using the fact that the width of a normal distribution at half its maximum height is approximately equal to 2.4 , where is the standard deviation. (On the graph in the figure, estimate the width of the distribution at half of the maximum height of the curve, and then divide the value by 2.4.)