The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 50 hours.It can be concluded that at least 89% of this brand of bulbs will last between _______.
A)1100 and 1300 hours
B)1150 and 1250 hours
C)1050 and 1350 hours
D)1000 and 1400 hours
E)950 and 1450 hours

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The Answer of The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 50 hours.It can be concluded that at least 89% of this brand of bulbs will last between _______.
A)1100 and 1300 hours
B)1150 and 1250 hours
C)1050 and 1350 hours
D)1000 and 1400 hours
E)950 and 1450 hours

The Mean Life of a Particular Brand of Light Bulb