Direct proportionality - practice problems

Two sequences of numbers are proportional if their corresponding elements have a constant ratio. Direct proportionality is the dependence of two quantities, such that the number of times one quantity increases, the other quantity increases as many times. In other words: direct proportionality is a relationship in which it applies: in what proportion one quantity changes, in that proportion the other quantity also changes.

For example:
For 1 euro, I buy 10 rolls, then for 2 euros I buy 20 rolls in the same store.
A car travels at a constant speed, then the distance traveled is directly proportional to the time spent traveling, with the speed being the constant of proportionality.

Number of problems found: 632

Do you have homework that you need help solving? Ask a question, and we will try to solve it.

We will send a solution to your e-mail address. Solved problems are also published here. Please enter the e-mail correctly and check whether you don't have a full mailbox.

Please do not submit problems from current active math competitions such as Mathematical Olympiad, correspondence seminars etc...