Question 326901
Let's find the probability that both are first graders.
P(1st 1st)=8/18={{{4/9}}}
P(2nd 1st)={{{7/17}}}
P(2 1st)={{{(4/9)(7/17)=28/153}}}
"At least 1 second grader" means "not both 1st graders".
P(both 1st)+P(not both 1st)={{{1}}}
P(not both 1at)=1-28/153={{{125/153}}}
P(at least 1 2nd)={{{125/153}}}