Researchers are designing a clinical trial to evaluate the effects of folic acid in delaying the progression of kidney disease. Patients will be randomised to receive either folic acid, or placebo. The outcome, homocysteine level (measured in mmol/L) is a marker of disease progression. The researchers would like to have 90% power to detect a difference between the groups of 3.0 mmol/L at a significance level of 0.05. Assume that both groups are the same size, and that the standard deviation of the homocysteine level is 7 mmol/L.

(i) The number of patients per group needed to achieve 90% power would be: per group (ii) What level of power (as a percentage, with no decimal places) would be achieved if there were 80 patients per group: % (iii)If the sample size were 80 patients per group, with the original desired power of 90%, what would be the minimum detectable difference (provide your answer as a numeric value to 1 decimal place): mmol/L