a new drug is being tested to measure its effectiveness in treating migraine headaches. the test drug is given to 110volunteers who suffer from migraine headaches, and a placebo is given to 110other volunteers who also suffer from migraine headaches. after two weeks, 83 of those who received the drug report an improvement in their migraine symptoms, and 18of those who received the placebo also report an improvement in symptoms. what percent of those who took the drug showed improvement? (round to the nearest whole number)