21. (20.51) The design of controls and instruments affects how easily people can

Question

21. (20.51) The design of controls and instruments affects how easily people can use them. A student project investigated this effect by asking 25 right-handed students to turn a knob (with their right hands) that moved an indicator by screw action. There were two identical instruments, one with a right-hand thread (the knob turns clockwise) and the other with a left-hand thread (the knob turns counterclockwise). Table 18.5 gives the times in seconds each subject took to move the indicator a fixed distance. TABLE 20.4 PERFORMANCE TIMES (SECONDS) USING RIGHT-HAND AND LEFT-HAND THREADS RIGHT LEFT RIGHT LEFT SUBJECT THREAD THREAD SUBJECT THREAD THREAD 107 118 103 113 105 130 101 138 118 87 116 75 137 105 133 108 115 170 103 87 166 146 123 135 112 93 76 116 78 15 17 104 19 20 21 78 107 84 148 147 89 78 100 89 85 10 23 24 25 103 123 13 116

Explanation / Answer

step 1 answer : true

step 2 answer option d

step 3 right hand people find the right hand threads easier to use (0.01<p<0.05)

option b

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