7.2. On Monday morning, several fishermen arrived at the lake. Later, one more joined them. Each day, each of the fishermen caught 10 fish. From Monday to Friday inclusive, they caught a total of 370 fish. On which day of the week did the late-arriving fisherman arrive at the lake?
Answer: on Thursday.

Fishermen who were fishing from Monday to Friday inclusive caught 50 fish each. Since $370=50 \cdot 7+20$, the late-arriving fisherman caught twenty fish.

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