In random samples of 250 persons with low incomes, 200 persons with average incomes, and 150 persons with high incomes, there were, respectively, 155, 118, and 87 who favor a certain piece of legislation. Use the 0.05 level of significance to test the null hypothesis θ1 = θ2 = θ3 (that the proportion of persons favoring the legislation is the same for all three income groups) against the alternative hypothesis that the three θ's are not all equal.