Expert: Abe Mantell - 8/23/2005

Question
Hello:

If a surgeon performed an operation that cured all patients except for 1/2 of 1% of those patients having the operation, can the percentage of 1/2 of 1% (1/2%) or the fractional amount of 1/200, be determined if fewer than 200 patients had the operation?

If I'm not mistaken, 1/2 of 1% or 1/200 indicates that 1 out of 200 patients were not cured from the operation.
If fewer than 200 patients had the operation, can the percentage of 1/2 of 1% who were not cured be possible?

I thank you for your reply.

Answer
Good question!

What you say is true, unless...we round-off!

Suppose 1 out of 134 people did not get cured.
1/134 is about 0.00746, which when rounded to
the nearest 0.5% is 0.5%!  If we round to the
nearest 0.1%, then we need atleast 182 people
(since 1/182 is about 0.00549).

Abe