Cooking: Proportions play an essential role in any dish; they bring the balance of flavors and the right consistency in the dish. The pancake holds good with the right proportion of flour to milk, and the cookies with butter to sugar. For example, right proportion: flour to milk in the pancake or butter to sugar in cookies.
Finance: Ratios in finance, such as debt-income ratios, will continue to be a key indicator of one's financial health. They assess an individual's or another entity's ability to manage debt effectively compared to his or her or their incomes.
Medicine: Dosages in medicine are often based on a patient's weight to ensure effectivity and minimal toxicity. This use of ratios ensures that each patient is dosed on an individual basis according to their particular requirements.
Engineering: In engineering, the use of ratios is to ensure that things are put into the right proportion, such as in concrete mixtures, where the amount of sand, cement, and water is put into the mixture in the right ratio to make it come out strong and not fragile.