Thread: help me which counting is correct

How many strings are there of four lowercase letters that have the letter x in them?

which of the following answer is correct?
1) 1x26x26x26 =
2)

please explain me

Originally Posted by zpwnchen

How many strings are there of four lowercase letters that have the letter x in them?
which of the following answer is correct?
1) 1x26x26x26 =
2)

please explain me

is the number of four letters strings which contain at least one x.
Is that what the question means.

is the number of four letters strings which contain exactly one x.

Originally Posted by Plato

is the number of four letters strings which contain exactly one x.

can you tell me why you multiply with 4? what is the concept behind?

You multiply by 4 because you have 4 ways to place x:

x _ _ _
_ x _ _
_ _ x _
_ _ _ x

Originally Posted by zpwnchen

can you tell me why you multiply with 4? what is the concept behind?

Please note my edit.
There are four places to put the one x.

that makes sense! thank you