The mean life of a particular brand of light bulb is 1200 hours and the standard...
The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 75 hours. Tests show that the life of the bulb is approximately normally distributed. What is the range of hours that approximately 68% of the bulbs will last?
Homework Answers
Sol:
Approxiamtely 68% of the bukbs will last within 1 standard deviations of the mean
=mean-sd,mean+sd
=1200-75,1200+75
=1125,1275
Range of the hours that approximately 68% of the bulbs will last between
1125 and 1275 hours.
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