In: Statistics and Probability
The average time taken for your Internet service provider to remotely resolve a trouble ticket has a Normal distribution with a mean of 4.3 hours and a standard deviation of 3.1 hours. One day your service provider selects 100 trouble ticket. What is a probability that an average time to resolved these 100 tickets will be less than 4 hrs?
Solution :
Given that,
mean = 
 = 4.3
standard deviation = 
 = 3.1
n = 100

= 4.3

=
  /
n = 3.1 / 
100=0.31
P(
< 4) = P[(
- 
) / 
< (4-4.3) /0.31 ]
= P(z <-0.97 )
Using z table
= 0.1660
probability= 0.1660