brand of crockpots has a mean high temperature of 260º F and a standard deviation of 3º F. If a

Question

brand of crockpots has a mean high temperature of 260º F and a standard deviation of 3º F. If acrockpot′
s
highest temperature is below 251º F or above 269º F, it is considered defective. What percentage of these pots can be expected to be defective

Answer 1

251 and 269 are 3 standard deviations from the mean 260.  Use the empirical rule to determine the answer

 

Answer 2

Obtain a z-score chart:

http://www.stat.ufl.edu/~athienit/TPentrables/Ztable.pdf

Low temp

z = (251 - 260) / 3

z = -9 / 3

z = -3

Percentage below is 0.13%

High temp

z = (269 - 260) / 3

z = 3

Percentage above is 0.13%