:2. Solution. Chi-square = (1750 - 1800)^2 / 1800 + (1800 - 1800)^2 / 1800 + (250 - 200)^2 / 200 = 13.9 The number of degrees of freedom is 3-1 = 2. Since 13.9 is bigger than 9.21, the observed signicance level is less than 1%.