During a test, the scientist may try to prove or disprove just the null hypothesis or test both the null and the alternative hypothesis. If a hypothesis specifies a certain direction, it is called one-tailed hypothesis.
A mountain pass (also called a gap, saddle, or col) is a passage over a mountain range. They typically occur in valleys between mountain ridges, in low points along mountain watersheds or just the lowest point on a mountain ridge between two peaks. They can be relatively short in length (the width of a ridge) or they can be valleys many miles long. Mountain passes are often the location where roads and railways are built to get through the mountains. Many of them have become famous throughout history for their importance in trade and commerce.
The Hagerman Pass is a high mountain pass, at an elevation of 11,939 ft (3,639 m) above the sea level, located near Leadville, Colorado, in USA. The pass crosses the continental divide in the Rocky Mountains of central Colorado in the United States.