Answer :
Answer:
0.000647588
Step-by-step explanation:
The normal probability function formula is:
[tex]f(x)={\frac {1}{\sigma {\sqrt {2\pi }}}}e^{-{\frac {1}{2}}\left({\frac {x-\mu }{\sigma }}\right)^{2}}}[/tex]
To find the probability that a lightbulb will last more than 1800 hours, we can plug in x = 1800, μ = 1500, and σ = 200
[tex]f(1800) = {\frac {1}{200 {\sqrt {2\pi }}}}e^{-{\frac {1}{2}}\left({\frac {1800-1500}{200 }}\right)^{2}}}[/tex]
[tex]f(1800) = {\frac {1}{501.3}e^{-1.125}}[/tex]
[tex]f(1800) = 0.000647588[/tex]
So the probability that a lightbulb will last more than 1800 hours is 0.000647588