Question

Question 1 1 pts The time it takes a service station to change the oil in a car is normally distributed with a mean of 20 minutes and a standard deviation of 5 minutes. What percentage of cars take longer than 30 minutes? Approximately 0% Approximately 2%. Approximately 14%. Approximately 100% Question 2 1 pts

Answer 1

X=time required to change the oil in a car

X~Normal($\mu,\sigma^2$)

#Given:

u=20,0 = 5

#Percentage of car takes longer than 30 times

ie P(X>30)

P(X>30)=1-P(X<30)

=1 - P(4=< 30 – 20

=1- P(Z<2)

#value of z is obtain from standard normal table

=1-0.9772

=0.0228

#Approximately 2% of car take longer than 30 minutes

#Option 2nd is correct