There are four entrances to the Government Center Building in downtown Philadelphia. The building maintenance supervisor would like to know if the entrances are equally utilized. To investigate, 400 people were observed entering the building. The number using each entrance is reported below. At the .01 significance level, is there a difference in the use of the four entrances?

Entrance Frequency

Main Street .........140

Broad Street ........120

Cherry Street .......... 90

Walnut Street ........ 50

Total 400