19. Consider the probability distribution P(1)-0.25, P(2)-0.5, P(3)-0.25. What i

Question

19. Consider the probability distribution P(1)-0.25, P(2)-0.5, P(3)-0.25. What is the st of this distribution a. 0.250 b. 0.125 c. 0.100 d. 0.707 e. None of the above 20. You own 10 shirts and have to choose 3 of them to bring on vacation. How many possible combinations of shirts can you bring on vacation? a. 30 b. 120 c. 720 d. 7 e. None of the above 21. There are six contenders, any of whom might win the New York Marathon. How many possibilities are there for the first three finishers in the race if the order of finish Is important? a. 18 b. 720 c. 120 d. 36 e. None of the above

Explanation / Answer

Ans:

mean=1*0.25+2*0.5+3*0.25=0.25+1+0.75=2

variannce=(1-2)2*0.25+(2-2)2*0.5+(3-2)2*0.25=0.25+0+0.25=0.5

standard deviation=sqrt(0.5)=0.707

option d is correct.

20)We have to choose 3 out of 10.

So,number of ways we can choose=10C3=(10*9*8)/(3*2*1)=720/6=120

Option b is correct.

21)Number of possibilities=6*5*4=120

Option c is correct.

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