A study suggests that airlines have increased restrictions on cheap fares by raising overnight requirements (The Wall Street Journal, August 19, 2008). This would force business travelers to pay more for their flights, since they tend to need the most flexibility and want to be home on weekends. Eight months ago, the overnight stay requirements were as follows: One night Two nights Three nights Saturday night
37% 17% 28% 18%
A recent sample of 644 flights found the following restrictions:

One night Two nights Three nights Saturday night
117 137 298 92

Required:
a. Calculate the value of the test statistic.
b. At a 5% significance level, what is the critical value?