SOLUTION: a small school bus contains 8 first graders and 10 second graders. if 2 children were ill, what is the probability that at least one of them is a second grader? thanks

Question 326901: a small school bus contains 8 first graders and 10 second graders. if 2 children were ill, what is the probability that at least one of them is a second grader?
thanks
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
Let's find the probability that both are first graders.
P(1st 1st)=8/18=
P(2nd 1st)=
P(2 1st)=
"At least 1 second grader" means "not both 1st graders".
P(both 1st)+P(not both 1st)=
P(not both 1at)=1-28/153=
P(at least 1 2nd)=

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