Ms. Robinson gave her class 12 minutes to read. Carrie read 51/2 pages in that time. At what rate, in pages per hour, did Carrie read?
1 1/10
22
27 1/2
66

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.