When you buy your favorite type of chocolate you are charged

When you buy your favorite type of chocolate you are charged by how much you want. The cost is therefore a function, because it depends on the number of ounces of chocolate you buy. That is, for each input (weight in ounces), there is one output (cost, say in dollars). By contrast the price of a house is not a function of the lot size on which a house is built because houses on the same size lot may sell for many different prices.

Describe an everyday situation between variables that is a function. Clearly explain why the relationship a function.

Describe an everyday situation between variables that is not a function. Clearly explain why the relationship is not a function.

Solution

a) The interest paid by the bank on some amount of money to the account holder is related to the (and directly proportional) to the time a certain amount is kept in a bank. Thus the new amount A in the bank is a function of the time till which the amount remains in the bank.

b) Rainfall does not depend on the time since it started to rain. So rainfall is not a function of time.