If you stand up straight for 1 hour, and then you jump for 1 hour, then how much time did you spend standing up straight?
1 hour 15 minutes, or 75 minutes. If you are standing up straight for 1 hour, then that's already 60 minutes. Then you start jumping for 1 hour. Half of that time you spend in the air, and the other half you spend on the ground. But half of that time that you spend on the ground, you are bending down, so that's only another 15 minutes you are standing up straight. There you have 1 hour 15 minutes (or 75 minutes).