Question: Q2: Prior to a study to investigate a new asthma drug, pulmonary function was tested in a group of 144 individuals with exercise-induced asthma. The mean value of forced vital capacity in the sample was 2.5 litres with sample standard deviation 0.55 litres.

(a) Construct a 95% confidence interval for the mean value of forced vital capacity in individuals with exercise-induced asthma.

(b) Estimate how large a sample would be needed in order to reduce the width of the interval to 0.1 litres.

(c) It is known that the mean value of forced vital capacity amongst the whole population is 2.65 litres. Test at the 1% level whether the data provides significant evidence that sufferers of exercise-induced asthma have reduced forced vital capacity.