that's very very confusing, the way to solve the problem is easy, but when I try to solve the exercises I always get it wrong not because it is easy to solve but always I am stating the null hypothesis in the wrong way I get everything right but the interpretation is always the opposite to that in the solution

Hello, Ahmed: As an alternative hypothesis, we state the desired and logical result we expect to obtain. For example, it is expected that a weight-loss program will help with losing weight, eating high-protein foods will help gain muscle, getting more sleep hours will help us be more productive, and so on.... The null hypothesis is a preliminary presumption that the changes obtained by the investigated variable is ineffective.

I have the same doubt: I have read on the PDF that the null hypothesis is "the status-quo. Everything which was believed until now that we are contesting with our test". In my opinion what was believed until now is that that weight-loss program works well, it's the status-quo because it's what people expect from it. Isn't it? Why?