Question

Question 18

The numbers of minutes that travellers arrives at the airport before their scheduled departure are approximately normally distributed with mean 80.5 and standard deviation 9.9. What proportion of travellers arrive at the airport more than 71.4 minutes before their departure?

Write only a number as your answer. Round to 4 decimal places (for example 0.0048). Do not write as a percentage.

Question 19

Natural Gas bills in a certain city have mean $110.46. Assume the bills are normally distributed with standard deviation $16.25. Find the value that separates the lower 64% of the bills from the rest.

Write only a number as your answer. Round to two decimal places (for example: 42.81). Do not write any units.

Question 20

A survey among freshmen at a certain university revealed that the number of hours spent studying the week before final exams was normally distributed with mean 36 and standard deviation 4.

Find percentile corresponding to p = 46% of the number of hours studying.

Write only a number as your answer. Round to two decimal places (for example: 20.81).

Answer 1