Discover the answers you need at Westonci.ca, where experts provide clear and concise information on various topics. Join our platform to connect with experts ready to provide precise answers to your questions in different areas. Connect with a community of professionals ready to help you find accurate solutions to your questions quickly and efficiently.

When a certain basketball player takes his first shot in a game he succeeds with prob. 1/3. If he misses his first shot, he loses confidence and his second shot will go with prob. 1/4. If he misses his first 2 shots, his third shot will go with pro. 1/5. If he misses his first 3 shots, his fourth shot will go with prob. 1/6. If he misses his first 4 shots, the coach will remove hom from the game. Assume that the player keeps shooting until he succeeds or he is removed from the game. Let X denote the number of shots he misses until his first success or until he is removed from the game.

Required:
a. Compute the p.m.f. of X.
b. Compute E[X]


Sagot :

Solution :

Let the number of the shots that the player while playing misses until the first success = x

The random variable X can take the values {0, 1, 2, 3, 4}

[tex]$P(x=0)$[/tex] = probability of the player that does not misses the 1st shot

The probability of the player that he success at the 1st shot = [tex]$\frac{1}{3}$[/tex]

[tex]$P(x=1)$[/tex] = probability of the player that misses the 1st shot but succeeds in his 2nd shot [tex]$=\frac{2}{3} \times \frac{1}{4}$[/tex]

               [tex]$=\frac{1}{6}$[/tex]

[tex]$P(x=2)$[/tex] = probability of the player that misses the 1st two shot but succeeds in the 3rd shot [tex]$=\frac{2}{3} \times \frac{3}{4}\times \frac{1}{5}$[/tex]

                                          [tex]$=\frac{1}{10}$[/tex]

[tex]$P(x=3)$[/tex] = probability of the player that misses the 1st three shot but succeeds in the 4th shot  [tex]$=\frac{2}{3} \times \frac{3}{4}\times \frac{4}{5} \times \frac{1}{6}$[/tex]

                                           [tex]$=\frac{1}{15}$[/tex]

Similarly,

[tex]$P(x)$[/tex] = (probability of missing the 1st four shots) x (probability of removing te player after the 1st four shots missed)

[tex]$=\frac{2}{3} \times \frac{3}{4}\times \frac{4}{5} \times \frac{5}{6} \times 1$[/tex]

[tex]$=\frac{1}{3}$[/tex]

a). The p.m.f of the X

X = x            0           1               2               3                 4

P(X=x)        [tex]$\frac{1}{3}$[/tex]             [tex]$\frac{1}{6}$[/tex]               [tex]$\frac{1}{10}$[/tex]             [tex]$\frac{1}{15}$[/tex]                [tex]$\frac{1}{3}$[/tex]          

b). [tex]$E(X) = \sum x \times P(X=x)$[/tex]

              [tex]$= 0\times \frac{1}{3}+1\times \frac{1}{16}+2\times \frac{1}{10}+3\times \frac{1}{15}+4\times \frac{1}{3}$[/tex]

             [tex]$=\frac{114}{60}$[/tex]

            = 1.9