Question

A 4-digit password is a number that begins with a 3 and does not contain a zero or nine. If digits can be repeated, how many possible passwords are there? A) 1,536. B) 512. C) 343

Answer 1

well , we now the password would be :

3 _ _ _ 

and if there is no 0 and 9, the combination must be between 1 to 8

So the possibility of password would be :

8 x 8 x 8 = 512 possibilities

The answer is option B.

Hope this helps

Answer 2

If digits can be repeated, the number of possible passwords are 512

How to determine the number of passwords?

The given parameters are:

Usable digits = 8 i.e. no 0 and 9

First digit = 3

Length = 4

The above parameters mean that:

• The first digit can only be 1 digit
• The other digits can be any of the 8 digits

So, the number of passwords is:

Combination = 1 * 8 * 8 * 8

Evaluate

Combination = 512

Hence, if digits can be repeated, the number of possible passwords are 512

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