During their school concerts, a middle school chorus stands on a set of platforms. Each platform is higher than the one in front of it so the audience can see all the singers in the chorus. The first platform, the one closest to the audience, is 6" high. The 5th platform, the one furthest from the audience, is 22" high. There is a constant difference in height between each pair of platforms. How much taller is the 4th platform than the 3rd platform? Answer: inches 4 Right! The student got this item correct. 18 Good try, but incorrect. That's the height of the 4th platform, but you needed to figure out how much taller it is than the 3rd platform. The correct answer is 4 inches. The student got this item incorrect. 6 Sorry, that was incorrect. That's the height of the 1st platform, but you needed to figure out how much taller the 4th platform is than the 3rd platform. The correct answer is 4 inches. The student got this item incorrect. Sorry, that was incorrect. You needed to figure out how much taller the 4th platform is than the 3rd platform. The correct answer is 4 inches. The student got this item incorrect. ModelArithmetic CommonDifference