A new type of smoke detector battery is developed From labor

A new type of smoke detector battery is developed. From laboratory tests under standard conditions, the half life (defined as less than 50% of the full charge) of 20 batteries are shown in the data set. Make a histogram of the data and normal probability plot. Do you think that the battery half life can be assumed to be normal? The engineers say that the mean battery half lifr will be 8760 hrs. with a std. dev. of 200 hrs. Using these parameters (not the sample) set up the centerline and control limits for the x-bar chart for a subgroup size of n=5 batteries to be sampled in future production runs. Repeat the previous exercise, but this time, use the sample mean and std. dev. Do you think that the control limits from this sample would be reliable. Explain, suggest alternatives.

Smoke Detector Battery Life (Hours)

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