Posted by Traci on .
40 students live in a dormitory. 5 have swine flu. If 4 students are selected at random, what is the probability that 1 or 2 of the 4 have swine flu?

Probability 
drwls,
Probability of 0: (35/40)(34/39)(33/38)(32/37) = 0.5729
Probability of 4: (5/40)*(4/39)*(3/38)*(2/37) = 120/2,193,360 = 0.000055
Probability of 1:
4*(35/40)*(34/39)*(33/38)*(5/37)= 0.3581
Probability of 2:
(4!/(2!*2!))(35/40)*(34/39)*(5/38)*(4*37)= 0.0651