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# standard deviation and t test

Problem 1. Confidence Intervals: t tests. Digitized Documents, Inc., is a small but rapidly growing firm in the digitized document translation business. The company reads architectural and engineering drawings into a scanning device that translates graphic information into a digitalized format that can be manipulated on a personal computer or work station. During recent weeks, the company has added a total of five new clerical and secretarial personnel to help answer customer questions and process orders. Data on the number of years of work experience for these five new workers is as follows:

5 4 3 4.5 3

A. Calculate the mean, median and mode measures of central tendency for the number of years of work experience. Which measure does the best job of describing central tendency for this variable? The mean is 3.9 years per worker. The median is 4. The mode is 3. Each measure of central tendency offers a highly similar view of the typical observation.

B. Calculate the sample range, variance and standard deviation for this data series, and the 95% confidence interval within which you would expect to find the population's true mean. The range for these workers if from 3 to 5 years experience. The sample variance is 0.8 (years squared) with a standard deviation 0.894427 years.

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