2. A biomechanist compared four commercial abdominal exercise machines with abdominal crunches done without equipment (control). To make the comparison, he attached electromyography electrodes to the upper rectus abdominus muscle in 10 male subjects and recorded the electrical activity (in millivolts) during exercise. Following are the results. Use a computer to solve this problem. Subject Machine 1 Machine 2 Machine 3 Machine 4 Control 920 913 1,005 811 905 566 580 767 833 833 328 293 300 290 367 568 555 637 484 557 248 267 167 312 331 815 606 607 462 459 313 264 252 295 314 538 502 399 354 506 1.475 1.563 1,174 1.722 1.581 465 434 375 300 352 Hint: Set up this data like the data in problem 1. Data courtesy of Dr. William Whiting, Director, Biomechanics Laboratory, Department of Kinesiology, California State Uni- versity Northridge a. What are the mean and standard deviation for each machine and control? b. Did any of the machines elicit more electromyographic activity in the upper rectus abdominus muscle than control conditions? c. What is the probability that the null hypothesis is true in this experiment? d. Is it necessary to perform a post hoc test in this experiment