Answer:
A Scientific experiment is designed in such a way that it should test the hypothesis.
The experiments contain three types of variables: independent variable-which can be manipulated, dependent variable- which has to be tested and the constant- which is kept constant throughout the experiment.
The scientific experiment can be categorized into two samples: the experimental group in which the dependent variable is tested and the control group in which the dependent variable is not present.
Therefore in the given question
1. independent variable- the amount of water which was changed throughout the experiment.
2. dependent variable- the endurance power measured.
3. hypothesis- If more water is consumed, then more endurance is observed in athletes.
4. Control group- No control group was included in the experiment.
5. Experimental group- the groups who drank water before practice
6. Constant- the number of players and water consumed per week.
7. The problem is that it lacked the reference group or control group which will provide the data to compare with.