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An instructor assigns 10 problems and says that the final exam will consist
of a random selection of 5 of them. If a student knows how to solve 7 of the problems,
what is the probability that he or she will answer correctly
a) all 5 problems
b)at least 4 problems
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(a) P = = = reduce = . ANSWER
The denominator is the number of all possible quintuples of 10 problems.
The numerator is the number of all possible quintuples of 7 known problems.
(b) P = = = = reduce = . ANSWER
The denominator is the number of all possible quintuples of 10 problems.
The numerator is the number of all possible quintuples containing 4 or 5 known problems.
Solved, with full explanations.