The question is irrelevant, since you couldn't find the dolls even if you knew how many. (Note: Well, this was a good joke in 1983-84. . . .)
or
None. There never was any light bulb.
Notes: Probably the only really good light bulb joke of 1984.
or
or
Answer: The back of his head.
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Three:
One to write the light bulb removal program,
one to write the light bulb insertion program, and
one to act as a light bulb administrator to make sure nobody else tries to change the light bulb at the same time.
or
Nothing, peanuts don't talk.
or