Question 75989: Juan Salvador just completed a study of the life expectancy of 100 light bulbs and discovered that the mean time that they lasted before burning out was 1,900 hours. If the standard deviation was 150 hours, the empirical rule allows Juan to conclude that approximately 68 of the bulbs burned out between _________ and _________ hours.
a. 1,750, 2,050
b. 1,800, 1,900.
c. 1,600, 2,200.
d. 1,450, 2,350.
Thank You!
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Juan Salvador just completed a study of the life expectancy of 100 light bulbs and discovered that the mean time that they lasted before burning out was 1,900 hours. If the standard deviation was 150 hours, the empirical rule allows Juan to conclude that approximately 68 of the bulbs burned out between _________ and _________ hours.
====================
68% of the population is within one standard deviation of the mean; one
to the left and one to the right.
One standard deviation to the left is 1900-150=1750 hrs
One standard deviation to the right is 1900+150=2050 hrs
------------------
Cheers,
Stan H.
|
|
|
