Option 2: Buy three group tickets and six single tickets, and the cost is 657×3+27×6=577 yuan.
Option 3: Buy two group tickets and 66 single tickets, and the cost is 657×2+27×66=627 (RMB).
(2) According to the amount of money spent in the above scheme, it is concluded that the total cost of purchasing three group tickets and six one-person tickets is the highest.
There are three different purchase schemes, and the cost of each scheme is 55: single ticket/group ticket/total cost/meta-scheme 1 7 4 677 scheme 6 3 577 scheme 3 66 2 627, so the answer is: 7, 4, 677, 6, 3, 577, 66, 2, 627, buy three.