1 point The lifetime of lightbulbs that are advertised to la

(1 point) The lifetime of lightbulbs that are advertised to last for 5800 hours are normally distributed with a mean of 5950 hours and a standard deviation of 300 hours. What is the probability that a bulb lasts longer than the advertised figure? Answer:

Solution

We first get the z score for the critical value. As z = (x - u) / s, then as          
          
x = critical value =    5800      
u = mean =    5950      
          
s = standard deviation =    300      
          
Thus,          
          
z = (x - u) / s =    -0.5      
          
Thus, using a table/technology, the right tailed area of this is          
          
P(z >   -0.5   ) =    0.691462461 [ANSWER]