A bond analyst was given a list of 13 corporate bonds. From
that list, she selected 4 whose ratings she felt were in danger of
being downgraded in the next year. In actuality, a total of 5 of
the 13 bonds on the list had their ratings downgraded in the next
year. Suppose that the analyst had simply chosen 4 bonds randomly
from this list. What is the probability that at least 2 of the
chosen bonds would be among those whose ratings were to be
downgraded in the next year?
The probability that at least 2 of the chosen bonds would be
downgraded is nothing.