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 between 375 and 425 pounds per square inch?
A) 95%
B) 68%
C) 84%
D) 32%
E) 47.5%

Question

Quizplus · Accepted Answer

The 68-95-99.7 Rule (or Empirical Rule) states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, 95% within two standard deviations, and 99.7% within three standard deviations. The range from 375 to 425 pounds per square inch is within two standard deviations (25 pounds, since 12.5 pounds is one standard deviation) of the mean (400 pounds), so approximately 95% of the tiles will have breaking strengths within this range.

Based on Data Collected from Its Production Processes, Crosstiles Inc