Question 810265
The lifetime of light bulbs that are advertised to last for 6200 hours are normally distributed with a mean of 6500 hours and a standard deviation of 150 hours. What is the probability that a bulb lasts longer than the advertised figure? 
-----------
z(6200) = (6200-6500)/150 = -2
-----
P(x > 6200) = P(z > -2) = normalcdf(-2,100) = 0.9772
=================
Cheers,
Stan H.
=============