In order to make observations, an observer must always use what?

Sciene is the subject

In order for a scientist to make observations. They must uses their senses.

Explanation:

The senses include:

Sight

Touch

Smell

Taste

Hearing

93.2 ml + 3920 ml = 4013 ml total  

(93.2 ml) * (2.03 m) / (4013 ml) = 0.0471 m

the volume in in l of the diluted solution would be 0.0471 m.

i think the answer is terrae but not 100 percent sure. ▓▬▬ §