The Springfield Emergency Medical Service keeps records of emergency telephone calls. A study of 150 five-minute time intervals resulted in the distribution of number of calls that follows. For example, during 18 of the 5-minute intervals, no calls occurred. Use the chi-square goodness-of-fit test and α = .01 to determine whether this distribution is Poisson.

Number of Calls
(Per 5-minute interval) ... Frequency
0 ............ 18
1 ............ 28
2 ............. 47
3 ............. 21
4 .............. 16
5 ............. 11
6 or more ........... 9