Which choice best explains the definition of a variable? 1.A variable is one way that scientists collect and record data in a scientific investigation.

2.A variable is something that can change and may affect the outcome in a scientific investigation.

3.A variable is a type of testable question that scientists ask when beginning a scientific investigation.

4.A variable is an educated guess that scientists make before conducting a scientific investigation.

I don't have the answer but...

Explanation:

A variable is a quantity that may change within the context of a mathematical problem or experiment. Typically, we use a single letter to represent a variable. The letters x, y, and z are common generic symbols used for variables.

A variable is a quantity that may change within the context of a mathematical problem or experiment. Typically, we use a single letter to represent a variable.

2b2t

explanation:

2b2t

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =