Question

What must be part of a quantitative observation? a change of state a change in size a number a color

Answer 1

I believe that the best answer among the choices provided by the question is the third choice , a change in number 
Hope my answer would be a great help for you.    If you have more questions feel free to ask here at Brainly.

Answer 2

The answer is: a number.

Observation is the active purchase of information from a primary source.

There are two types of data collecting: quantitative and qualitative observations.  

1) Quantitative observations are made with instruments.  

This data are measurable and can be expresed with numbers.  

2) Qualitative observations are information about the quality of substances.  

In qualitative observation, informations are collected using senses (sight, hearing, taste, smell and touch).  

Qualitative observations are not measurable and cannot be recorded in terms of numbers.