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View Full Version : Standard deviation with 95% certainty, two parts.


NightWing
Oct 31, 2009, 08:57 PM
By measuring the amount of time it takes a component of a product to move from one workstation to the next, an engineer has estimated that the standard deviation is 4.0 seconds.

Answer each of the following (show all work):

(A) How many measurements should be made in order to be 95% certain that the maximum error of estimation will not exceed 1 second?

(B) What sample size is required for a maximum error of 2 seconds?

galactus
Nov 1, 2009, 06:58 AM
To find the sample size use the formula E=z\cdot \frac{\sigma}{\sqrt{n}}.

Plug in your knowns and solve for n.

You are given E and \sigma

The z score that corresponds to a 95% CI is 1.

You will get a decimal solution, so always round up your answer to the next highest integer.