Question: What is the question to be answered in completing this problem?
Most traffic lights are set so that there is enough time for pedestrians to cross the road safely. A recent study indicates that a large number of elderly cannot get across the road in the usual 15 seconds allowed. To determine the average amount of time it takes senior citizens to cross the street, a study was taken of 25 seniors. On the average, it took them 19.5 seconds to cross the street, with a sample standard deviation of five seconds. Assume the time to cross the road has a normal distribution.
The question probably is: Is the average time for the elderly to cross the street more than 15 seconds?
From a statistical sample, ...
The solution answers the question(s) below.