David did not measure the solutions' volumes before mixing the solutions.
Since you did not tell us what Maria's hypothesis was or how she tested it, we cannot provide an answer.
1:They are based on observations. 2:They can be tested
That is progress, you start with a hypothesis, e.g. the moon is made of cheese, then it is tested by experiments to see if it's right. If the experiment says it's wrong, that is something that does not have to be tested again.
it depend if the hypothesis is good or wrong. depends if the hypothesis is correct. An hypothesis is, in simple terms, a "guess" based on observed data. For this reason, the data to support any hypothesis can be manipulated to prove it either "right" or "wrong". Neither is more helpful. All scientific endeavour should be tested and retested.
conducting experiment
A hypothesis that can't be tested, can't be proved.
A hypothesis is tested by an experiment. A hypothesis is an estimate or guess about an outcome. The experiment proves whether the hypothesis is correct or not correct.
A hypothesis can be tested by an experiment
Not unless its tested by experimentation. If its tested by experimentation. And then if found to be true its no longer just a hypothesis. And if found to be false it becomes an invalid hypothesis, which anyone in their right mind would withdraw as a hypothesis.
A hypothesis is tested by having trials
hypothesis
An hypothesis is a concept or an idea to be tested.