The company has agreed on an 8 character password format, comprised of upper case letters , lower case letters, and digits (0-9). Find the number of passwords possible where the first 2 characters have to be upper case letters, the next 5 can be lower case letters or digits , and the last character has to be an upper case letter. Here are the restrictions: a. Repetitions are allowedb. Repetitions are not allowed
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 company has agreed on an 8 character password format, comprised of upper case letters , lower case letters, and digits (0-9). Find the number of passwords possible where the first 2 characters have to be upper case letters, the next 5 can be lower case letters or digits , and the last character has to be an upper case letter. Here are the restrictions:
a. Repetitions are allowed
b. Repetitions are not allowed
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