The time needed to complete a final examination in a particular college course i

Question

The time needed to complete a final examination in a particular college course is normally distributed with a mean of 80 minutes and a standard deviation of 10 minutes. Answer the following questions. Round the intermediate calculations for z value to 2 decimal places.

Assume that the class has 60 students and that the examination period is 90 minutes in length. How many students do you expect will be unable to complete the quiz the allotted time (to the next whole number)?

New York City is the most expensive city in the United States for lodging. The mean hotel room rate is $204 per night (USA Today, April 30, 2012). Assume that room rates are normally distributed with a standard deviation of $55.

What is the probability that a hotel room costs less than $139 per night (to 4 decimals)?

Explanation / Answer

Assume that the class has 60 students and that the examination period is 90 minutes in length. How many students do you expect will be unable to complete the quiz the allotted time (to the next whole number)?

= P (z > 90)

= P (z > 90-80/10)

= P (z > 0.83)

= 1 - P (z < 0.83)

= 1 - 0.7967

= 0.2033 or 20.33%

New York City is the most expensive city in the United States for lodging. The mean hotel room rate is $204 per night (USA Today, April 30, 2012). Assume that room rates are normally distributed with a standard deviation of $55.

What is the probability that a hotel room costs less than $139 per night (to 4 decimals)?

= P(X<139)
= P(Z< (139-204)/55)
= P(Z<-1.18181818) or 1.1818
= 0.1401

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