QUESTION 5 To study how the design of controls and instruments can effect how easily people can use them, a study asked 25 right-handed people to turn a knob (with their right hands) which moved an indicator by screw action. Each person did this on two otherwise identical instruments; one with a right-hand thread (the knob turns clockwise) and one with a left-hand thread (the knob turns counterclockwise). The time required (in seconds) to move the indicator a fixed distance was recorded. The differences in times (recorded as left-hand thread time minus right-hand thread time) were calculated. These differences have a mean of 13.32 seconds and a standard deviation of 22.94 seconds. Researchers want to determine if all right-handed people can more easily use the instruments with a right-hand thread (that is, if the mean time is faster for right-handed people on instruments with a right-hand thread than on instruments with a left-hand thread). What is the value of the test statistic given the implied null and alternative hypotheses