Aquality control engineer at a potato chip company tests the bag filling machine by weighing bags of potato chips. not every bag contains exactly the same weight. but if more than 15% of bags are over-filled then they stop production to fix the machine. they define over-filled to be more than 1 ounce above the weight on the package. the engineer weighs 100 bags and finds that 21 of them are over-filled. he plans to test the hypotheses: h0: p = 0.15 versus ha: p > 0.15 (where p is the true proportion of overfilled bags). what is the test statistic?