Based on data collected from its production processes Crosst

Based on data collected from its production processes, Crosstiles Inc. determines that the breaking strength of its most popular porcelain tile is normally distributed with a mean of 400 pounds per square inch and a standard deviation of 12.5 pounds per square inch. Based on the 68-95-99.7 Rule, about what percent of its popular porcelain tile will have breaking strengths greater than 412.5 pounds per square inch

Solution

400 + x*12.5 = 412.5

x = 1

based on 68-95-99.7

mean +/- 1*SD = 68%

greater than 412.5 that is + 1SD about the mean is 68/2 = 34%

or you can use the z formula and see the rpobability in the tables of normal distibution

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