Indicate the null (H0) and alternative hypothesis (Ha)

Question

Indicate the null (H0) and alternative hypothesis (Ha) you would develop for the following problems (I do not have to solve the problem)

a) 5% of trucks of a certain model have needed new engines after being driven between 0 and 90 miles. The manufacturer hopes that the redesign of one of the engine's components has solved this problem.

b) A weight loss center provided a loss for 87% of its participants. The center's leader decides to test a new weight loss strategy to see if it's better.

Answer 1

The null hypothesis is the proposition that observed conditions are a result of chance and not directly related to a proposed cause.  The alternative hypothesis proposes that there is a cause and effect relationship between certain conditions and a specific action or event.  In this case you need to determine what are 1) the effects under observation, 2) what is the action or event which it is proposed will have a causal relationship with these effects, and 3) what  statement can be made about the conditions given that no causal relationship exists?  Once you get these then simply formulate them into cohesive statements expressing the two hypotheses.