A password is 4 characters long and must consist of 3 letters and 1 of 10 special characters. If letters can be repeated and the special character is at the end of the password, how many possibilities are there?

The special character must be at the end, so only the first three positions need to be filled with letters. Each position has 26 choices, and letters can repeat, giving 26 × 26 × 26 = 17,576 letter combinations. The final position has 10 choices, so the total is 17,576 × 10 = 175,760 possibilities. This matches choice A, 175,760.

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