Answer:
The probability that a randomly chosen light bulb will last less than 900 hours is 0.1587.
Step-by-step explanation:
The life span of these light bulbs is normally distributed with a mean of 1000 hours and a standard deviation of 100 hours
Mean = [tex]\mu = 1000 hours[/tex]
Standard deviation =[tex]\sigma = 100 hours[/tex]
We are supposed to find the probability that a randomly chosen light bulb will last less than 900 hours.i.e. P(x<900)
So, [tex]Z=\frac{x-\mu}{\sigma}[/tex]
[tex]Z=\frac{900-1000}{100}[/tex]
Z=-1
P(x<900)=P(z<-1)=0.1587
Hence the probability that a randomly chosen light bulb will last less than 900 hours is 0.1587.
