Alice has a frequent customer card with her favorite ice cream store. When she first gets her card, the owner of the ice cream store puts 3 stamps on it. After that, Alice gets 2 stamps on her card each time she buys an ice cream cone. Once she has earned at least 15 stamps, Alice can exchange her card for a Super Deluxe Chocolate Peanut Butter sundae. How many ice cream cones must Alice buy before she can earn the sundae? Enter your answer here: 6 Right! The student got this item correct. 15 Sorry, that's incorrect. That's the total number stamps that Alice needs. Since she started with 3 stamps, she needs fewer than 15 cones. But she also earns 2 stamps per cone. The correct answer is 6 cones. Student probably selected the total number of stamps. 8 Good try, but you didn't figure in the three stamps that Alice started with. The correct answer is 6 cones. Student figured that 2*8=16, enough stamps to get the free sundae. Sorry, that was incorrect. Starting with the original 3 stamps, Alice needs to buy 6 cones to earn the additional 12 stamps (2 stamps per cone) to bring her to 15. The student did not get this item right. ModelArithmetic ExtendArithmetic