Investigators are studying two drugs used to improve the FEVl readings (a measure of lung function) in asthmatic patients. Assume that  = .8 and the difference in means they wish to detect is .25. If...

Investigators are studying two drugs used to improve the FEVl readings (a measure of lung function) in asthmatic patients. Assume that
 = .8 and the difference in means they wish to detect is .25. If they want to do a two-sided test of equal population means with
 = .05 and
 = .20, what sample size should they use?