Time remaining:
Need help with a normal percentile question

Statistics
Tutor: None Selected Time limit: 0 Hours

The Dmv reports that the average age of a vehicle in Santa Clara County is 9 years old (108 months) with a standard deviation of 18 months. For a random sample of 20 vehicles in Santa Clara County what is the probability that the average age of the vehicles in the sample is more than 10 years old (120 months). 

Give your answer to a decimal rounded to the fourth decimal place.

Apr 12th, 2015

The standard deviation of average age of 20  vehicles is 18/sqrt(20) = 4.025 months. 

for 120 month the z score is 

(120-108)/4.025 = 2.9814 

Pr (X>120) = Pr(Z>2,9814) = 1-Pr(Z<2.9814) = 1-0.9986 = 0.0014


Apr 13th, 2015

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.
Click to visit
The Notebank
...
Apr 12th, 2015
...
Apr 12th, 2015
Dec 3rd, 2016
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer