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Nov 2016 p62 q2
2917
Noor has 3 T-shirts, 4 blouses and 5 jumpers. She chooses 3 items at random. The random variable X is the number of T-shirts chosen.
Show that the probability that Noor chooses exactly one T-shirt is \(\frac{27}{55}\).
Draw up the probability distribution table for X.
Solution
(i) To find the probability that Noor chooses exactly one T-shirt, we use combinations. The total number of ways to choose 3 items from 12 is given by \(\binom{12}{3}\).
The number of ways to choose 1 T-shirt from 3 is \(\binom{3}{1}\), and the number of ways to choose 2 items from the remaining 9 (blouses and jumpers) is \(\binom{9}{2}\).