How many 0.5 do I need to get an average of 0.05?

2011-09-14T20:41:31Z

If the uncertainty of a single length measurement is ±0.5 cm, how many measurements, N, of the same length are necessary so that the average of the measurements has an uncertainty of ±0.05cm?

Anonymous2011-09-14T20:39:31Z

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i think you are asking (0.5) ^ x = 0.05

you will need a scientific calculator that can do inverse exponents
because 0.5 = 1/2 and 0.05 = 5/100 = 1/20 and there is no integral
power of 2 that equals 20.

the approximate power is 4.47 (scientific calc.)

however, you have used the word "average" in your question,
and since 0.5 is bigger than 0.05 it doesn't make sense to me.

double check the question and re-submit?