# Which is an example of a direct variation? ?

A)Tires on a car and number of cars

B)Number of people at a starting line in a race. The individual speed of a runner in feet per second.

C) Number of balloons in a bunch. The rate I can pop them in pops per second.

### 1 Answer

- Steve4PhysicsLv 73 weeks agoFavorite Answer
Direct variation (sometimes called direct proportion) means if one thing changes by some factor, another thing changes by the same factor.

For example: doubling one thing doubles the other; making one thing 7 times smaller makes the other thing 7 times smaller.

________________

There is a mistake in the question. None of the answers shows direct variation.

A)Tires on a car and number of cars

There are 4 tires on car; doubling (for example) the number of cars does not give 8 tires on a car.

__________

B )Number of people at a starting line in a race. The individual speed of a runner in feet per second.

Doubling the number of people does not double a runner’s speed

__________

C) Number of balloons in a bunch. The rate I can pop them in pops per second.

Doubling the number of balloon does not double how fast you can pop them (you can’t move your hand faster just because there are more balloons).

Check you have the correct wording for the question. Question A would be direct variation if it said “Total number of tires and number of cars" because doubling the number of cars would double the total number of tires

That's why I gave a reworded version of option A which *does* show a direct variation!