The Honest Lock Co. plans to introduce what it refers to as the “true combination lock.” The lock will open if the correct set of 3 characters from the following (familiar) set of 26 characters {a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z} is entered (in any order). If it is allowed that any or all of the characters may be the same, what is the total number of combinations possible?
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.
The Honest Lock Co. plans to introduce what it refers to as the “true combination
lock.” The lock will open if the correct set of 3 characters from the following (familiar) set of 26 characters
{a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z}
is entered (in any order).
If it is allowed that any or all of the characters may be the same, what is the total number of
combinations possible?
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