Mathematics
MarceleneZuerlein724
28

The length of a screw produced by a machine is normally distributed with a mean of 0.55 inches and a standard deviation of 0.01 inches. What percent of screws are between 0.53 and 0.57 inches? 99.7% 68% 95% 100%

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Sergio14

Find the relation between the range, the standard deviation and the media: 0.57 = 0.55 + 0.02 = 0.55 + 2*0.01 = media + 2* standard deviation 0.53 = 0.55 - 0.02 = 0.55 - 2*0.01 = media - 2 * standard deviation Then, the desired range is media +/- 2 * standard deviation. In normally distributed functions, this correspond to 95% confidence interval. Then, the answer is the third option shown, 95%

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