# How many variables are altered in a good experiment?

Answer: An experiment usually has three kinds of variables: independent, dependent, and controlled. The independent variable is the one that is changed by the scientist. Why just one? Well, if you changed more than one variable it would be hard to figure out which change is causing what you observe.

There's three kind of variables which are Independent, dependent, and controlled.

Explanation:

## Related Questions

How long should concrete be allowed to set before it is ready to be used? 7 days
14 days
28 days
35 days

In standard industrial cases, full strength concrete is recognized at 28 days. At seven days, you should have concrete that is cured to 70% full strength or greater. hope this helped!

The concrete should be let to set for 28 days

All but one of the conditions will increase the reaction rate of an enzyme. The condition that will NOT increase the reaction rate is

decreasing the concentration of the enzyme.

Explanation:

The planet earth is a closed system where materials cycle between the lithosphere, atmosphere, hydrosphere and biosphere. It does not lose materials  to the outside and neither does it receive any from outer space.

The water that has been there since the earth was created is still the same. It is used and recycled over and over again through the hydrologic (water) cycle. It is never lost. but  changes its form from liquid to vapor to ice or snow then back to liquid in a continuous cycle.

Which of the following is most likely to be a limiting factor for growth on the floor of a tropical rainforest? a.

water

b.

shelter

c.

sunlight

d.

prey