Analysis: according to the meaning of the question, the coat needs 108 yuan, and the pants need 289 yuan. So a suit includes a coat and trousers, so the price of a suit should be

108 yuan +289 yuan =397 yuan.

Because 397 < 400,400 yuan is enough to buy such a suit.

The knowledge of this exam is mainly a three-digit ratio. The price of a suit is equivalent to the price of a coat and trousers. As long as this number is less than 400, you can buy a suit. The percentile 3 of 397 is less than the percentile 4 of 400, so 397 is less than 400. Then you can buy this suit.