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 overfilled 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 h 0: p = 0.15 versus h a: p > 0.15. what is the test statistic? group of answer choices z = − 1.47 z = − 1.47 z = − 1.47 z = − 1.47 z = 4 z = 4 z = 4 z = 4 z = 1.68 z = 1.68 z = 1.68 z = 1.68