How many different passwords can be made if it is three letters, followed by two digits, followed by a letter? (Repetition is allowed.) Use the fundamental counting principle.

There are 45,697,600 different passwords.

Step-by-step explanation:

Fundamental counting principle:

States that if there are p ways to do a thing, and q ways to do another thing, and these two things are independent, there are p*q ways to do both things.

In this question:

3 letters, each with 26 possible options(ways).

Two digits, each with 10 possible options.

One digit, with 26 possible options.

How many different passwords?

Each digit/letter is independent, so:

26*26*26*10*10*26 = 45,697,600

There are 45,697,600 different passwords.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.