# SOLUTION: Hello there, I need your help on probability-tree diagram. I'm very thankful if anyone could help me on this. Thanks! In a class, the probability that a student wears a watch is

Algebra ->  Algebra  -> Probability-and-statistics -> SOLUTION: Hello there, I need your help on probability-tree diagram. I'm very thankful if anyone could help me on this. Thanks! In a class, the probability that a student wears a watch is      Log On

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 Click here to see ALL problems on Probability-and-statistics Question 596322: Hello there, I need your help on probability-tree diagram. I'm very thankful if anyone could help me on this. Thanks! In a class, the probability that a student wears a watch is 0.8. Three students are randomly selected from the class. (A) Draw a tree diagram showing all posible outcomes and their probabilities. (B) What is the probabilty that (i) all three students wear a watch (ii) only te first three student wears a watch (iii) only one student does not wear a watch (iv) none of the three student wears a watchAnswer by stanbon(57290)   (Show Source): You can put this solution on YOUR website!In a class, the probability that a student wears a watch is 0.8. Three students are randomly selected from the class. (A) Draw a tree diagram showing all posible outcomes and their probabilities. ----- Note: You did not post the number of students in the class. You only indecated that 3 were selected. --- Let the Root column be A ; B ; C ; etc. (depending on number in the class = n). --- To the right of the Root column put the 1st Branch column which has "watch" ; "no watch" to the right of each Root element. That column should have 2n elements in it. --------------------------------------- Next to each "watch" put 0.8 Next to each "no watch" put 0.2 ======================================= (B) What is the probabilty that (i) all three students wear a watch: nC3*0.8^3*0.2^(n-3) -------------------- (ii) only the first three student wears a watch: 0.8^3*0.2^(n-3) ------------------------ (iii) only one student does not wear a watch: nC1(0.2)*0.8^(n-1) ------------------------------------- (iv) none of the three student wears a watch: nC3(0.2)^3*0.8^(n-3) ==================================== Cheers, Stan H. ====================================