How many 3-digit numerical passwords are there if a digit cannot be repeated?
1 answer:
The first digit of the password can be any of the ten digits - 10 possibilities.
A digit cannot be repeated, so the second digit can be any digit except the one you chose for the first digit - 9 possibilities.
The third digit can be any digit except the digits you chose for the first and second digit - 8 possibilities.
Using the rule of product:
There are 720 passwords.
A digit cannot be repeated, so the second digit can be any digit except the one you chose for the first digit - 9 possibilities.
The third digit can be any digit except the digits you chose for the first and second digit - 8 possibilities.
Using the rule of product:
There are 720 passwords.
You might be interested in
Answer:
15 miles
Step-by-step explanation:
Let's say the dock is at the origin on a coordinate plane and each unit is 1 mile. If the boat travels 9 mile due north, that means that we move up from the origin (0, 0) 9 units to point A (0, 9). Now, this boat moves 12 miles due west, so we will go 12 units to the left of (0, 9) to point B (-12, 9). See the attached drawing (sorry for the crudeness).
Notice that this is a right triangle with legs of 9 and 12. That means the distance from the boat to the dock is just the hypotenuse, so use the Pythagorean Theorem: distance =
Thus, the answer is 15 miles.
Hope this helps!
