With the addition of a single letter, the words below can be anagrammed into new words. The added letter is the same for all the words. What is the letter, and what are the new words?

1. DIME
2. INTO
3. LUTE
4. THIS
5. ROBE

Answers:

The letter is X:

1. MIXED
2. TOXIN
3. EXULT
4. SIXTH
5. BOXER

Credit:  GAMES Magazine
July, 1991
Charles Connolly
MARK MY WORDS 

[See also similar puzzle posted 2/11/16]