HOW MANY DIFFERENT ARRANGEMENTS ARE THERE OF THE LETTERS IN TESTERS?

Answer 1

This is a permutation.

n! (n factorial) = n(n-1)(n-2)...1

What is your n?

http://en.wikipedia.org/wiki/Permutation

I hope this helps. Thanks for asking.

Answer 2

My solution assumed that each letter — even if repeated — was considered different. Thus T1 is considered different from T2 and so on.

I hope this helps a little more. Thanks for asking.