Question 1047389
10. Suppose that a certain brand of light bulbs has a mean life of 600 hours and a standard deviation of 53 hours. 
According to the Empirical Rule: 
one  standard deviation from the mean accounts for about 68% of the set 
two standard deviations from the mean account for about 95%
and <u>three standard deviations</u> from the mean account for about 99.7%.

99.7% of light bulbs have a lifetimes between 600 -159 and  600 + 159. 

11. Using information from #10, what percentage of light bulbs will last between 547 and 706 hours?
The TI syntax is normalcdf(smaller, larger, µ, &#963;).
p = normalcdf(547, 706,600, 53)= .8186  0r 81.86%
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Recommend Using stattrek.com to check  Results
until You are familiar with Using Your Calculator.
One could also Use Your Casio fx-115 ES plus 0r fx-991 ES plus