au may ue you aleulalar and one 8.311mote sheet.I recommend using Cirele the bes
ID: 3324586 • Letter: A
Question
au may ue you aleulalar and one 8.311mote sheet.I recommend using Cirele the best choice or Bll-in the correet answer. v You are free to provide your answer if you do not like any of the wultiple choice options A local trade union consists of 75 plumbers and 50 electricians. Classified according points to rank: Apprentice Journeyman Master Totals 14 38 Electricians 1 8 Plumber-t20 Totals 80 125 40 A member of the union is selected at random. Given that the person selected is a master find the probability that she is a plumber (a) 22/125 (b) 22/80 (c) 22/40 (d) 40/125 (e) 80/45 M In a group of high-school students, 25% tease other students, 35% talk in class, and 10% do both. What is the probability that a randomly selected student from the group has at least one of these bad habits? (a) .30 (b) 40 (e) .50 (d).60 (e).70 Let X be a random variable with probablity mass function f given in the table below. What is the mean or expected value of X? (e) 1 0.3 1 0.1 tat 0.10 (a) 14 (e) 2.0Explanation / Answer
1) Given that the person is master, probability that she is a plumber is computed here using bayes theorem as:
= n( master and plumber ) / P( master )
= 22 / 40 = 0.55
Therefore C is the required probability here.
2) Here we are given that: P( tease ) = 0.25, P( talk ) = 0.35 and P( both ) = 0.10
Using addition law of probability, we get:
P( tease or talk ) = P( tease ) + P( talk ) - P( both ) = 0.25 + 0.35 - 0.10 = 0.50
Therefore C is the required probability here.
3) The expected value of X here is computed as:
E(X) = 0*0.3 + 1*0.1 + 2*0.4 + 3*0.1 + 4*0.1 = 0.1 + 0.8 + 0.3 + 0.4 = 1.6
Therefore B is the required probability here.
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