The observed numbers of days on which accidents occurred in a factory on three successive shifts over a total of 300 days are as shown below. The numbers of days without accidents for each shift were...

The observed numbers of days on which accidents occurred in a factory on three successive shifts over a total of 300 days are as shown below. The numbers of days without accidents for each shift were obtained by subtraction.

Totals for all rows and all columns have been calculated. Is the difference in number of days with accidents between different shifts statistically significant? That is, is there evidence that the probability of accidents depends on the shift? Use the 5% level of significance.