To test the given claim using two proportion z test.
Presume the manufacturer of Advil, a common headache remedy, recently developed a new formulation of the drug that is claimed to be more effective. To find out the new drug, a sample of 200 current users is asked to try it. After a one-month trial, 180 indicated the new drug was more effective in relieving a headache. At the same time a sample of 300 current Advil users is given the current drug but told it is the new formulation. From this group, 261 said it was an improvement. At the .05 significance level can we conclude that new drug is more effective?