The length of Super Bowl commercials is said to be Normally distributed with a mean of 36 seconds and standard deviation of 8 seconds.

Question

a. Find the probability that a randomly selected Super Bowl commercial is shorter than 45 seconds? (2 points)
b. Find the probability that a randomly selected Super Bowl commercial is between 30 and 50 seconds long? (3 points)
c. Budweiser commercials always seem to fall into the longest 4% of Super Bowl commercials. That means that Budweiser commercials are at least how long? (3 points)

Answer 1

David Lane's webpage is perfect for this type of question and replaces the charts and tables found in the back of textbooks

http://davidmlane.com/hyperstat/z_table.html

Just fill in the data
for c) remember that 96% would be shorter.
You might want to use the second feature of this calculator.