Let x be the number of courses for which a randomly selected

Let x be the number of courses for which a randomly selected student at a certain university is registered. The probability distribution of x appears in the table shown below:

Solution

a) P( x =4 ) =0.25

b) P(x<=4) = 0.02 + 0.02 + 0.07 + 0.25 =0.36

c) P ( atmost 5 courses ) = P(x<=5) = P(x =4) + p(x=5 ) = 0.36 + .43 = 0.79

d) P ( atlest 5 courses ) = P (x>=5) = 0.43 + 0.16 +0.05 = 0.64

P ( more than 5 courses ) = P ( x>5) = 0.16+0.05 = 0.21.

e) P( 3<= X <= 6) = 0.91

P ( 3 < X < 6 ) = 0.43 + 0.25 = 0.68