7.1. Each student in class 7B ate the same number of chocolate bars during math lessons over the week. Nine of them together ate fewer than 288 chocolate bars in a week, while ten of them together ate more than 300 chocolate bars. How many chocolate bars did each student in class 7B eat? Explain your answer.
Answer: 31 chocolates each

Solution 1: Since ten students ate more than 300 chocolates, nine students ate more than (310:10)$\cdot$9 = 270 chocolates. It is also known that nine students together ate less than 288 chocolates. The only number divisible by 9 in the range from 271 to 287 is 279. Therefore, nine students ate 279 chocolates, and one student ate 31 chocolates.

Solution 2: Since nine students together ate less than 288 chocolates in a week, one student ate less than $288: 9=32$ chocolates in a week. Since ten students together ate more than 300 chocolates in a week, one student ate more than 300:10 = 30 chocolates in a week. Ultimately, each student ate more than 30 but less than 32, i.e., 31 chocolates.

Criteria: Only the answer - 0 points. 7 points for the correct answer with correct reasoning. 3-5 points for partial progress in the solution.