Unclear question. However, I inferred you want to know about hypotehsis test.
Explanation:
Remember, any hypothesis test is divided into two types. They are:
- the null hypothesis and
- the alternate hypothesis.
Using this question example, here's the hypothesis statements ma sound:
Null hypothesis; There is a significant impact by the explanatory variables on engine overhaul time.
Alternate hypotheses; There is no impact by impact by the explanatory variables on engine overhaul time.