Question

1-4.5 A company manufactures small electric motors having horse power ratings of 0.1, 0.5, or 1.0 horsepower and designed for operation with 120 V single-phase ac, 240 V single-phase ac, or 240 V three-phase ac·The motor types can be distinguished only PROBLEMS by their nameplates. A distributor has on hand 3000 motors in the quantities shown in the table below Horsepower 20 Vc 240 V ac 240 V 30 900 200 100 400 500 200 100 600 0.5 One motor is discovered without a name plate. For this motor determine the probability of each of the following events. a) The motor has a horsepower rating of 0.5 hp. b) The motor is designed for 240 V single-phase operation. c) The motor is 1.0 hp and is designed for 240 V three-phase operation. d) The motor is 0.1 hp and is designed for 120 V operation. 1-4.6 In Problem 1-45, assume that 10% of the motors labeled 120 V single-phase are mismarked and that 5% of the motors marked 240 V single-phase are mismarked. a) If a motor is selected at random, what is the probability that it is mismarked? b) If a motor is picked at random from those marked 240 V single-phase, what is the probability that t is mismarked? c) What is the probability that a motor selected at random is 0.5 hp and mismarked?

Answer 1

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