Question 1120175: • Suppose you are interested in how long it takes to get your food at a restaurant. Now, suppose this distribution is approximately normal with an average of eight minutes and a standard deviation of two minutes. If you made a control chart for this data, what would be the highest control limit?
A) Suppose someone gets the food after exactly 11 minutes. How many standard deviations from the mean is this value of 11?
B) What is the probability that someone would get the food after more than 11 minutes?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! For A, (x-mean)/sd is the sd from the mean. (11=8)/2=1.5 sd from the mean.
If normal distribution, that is a z-value of +1.5, and the probability of something greater than that is 0.0668.
If you set control limits as mean+/-3 sd, that would be 14 minutes (8+3(2)) for the upper limit.
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