A man has seven keys on a key ring, one of which fits the door he wants to unlock. He randomly selects a key and tries it. If it does not unlock the door, he randomly selects another key from those remaining and tries to unlock the door with it. He continues in this manner until the door is unlocked. Let X be the number of keys he tries before unlocking the door, counting the key that actually worked, Find the exnected valug and th
Permutations and Combinations
If there are 5 dishes, they can be relished in any order at a time. In permutation, it should be in a particular order. In combination, the order does not matter. Take 3 letters a, b, and c. The possible ways of pairing any two letters are ab, bc, ac, ba, cb and ca. It is in a particular order. So, this can be called the permutation of a, b, and c. But if the order does not matter then ab is the same as ba. Similarly, bc is the same as cb and ac is the same as ca. Here the list has ab, bc, and ac alone. This can be called the combination of a, b, and c.
Counting Theory
The fundamental counting principle is a rule that is used to count the total number of possible outcomes in a given situation.
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