Alan leaves Los Angeles at 8:00 a.m. to drive to San Francisco, 400 mi away. He

25 min, 48 sec

Explanation:

Alan:

t = d/v

  = 400 mi / 46 mph = 8.70 hr

So it took Alan 8.70 hrs; from 8 am, that's 4:42 pm that he arrives.

t = d/v

  = 400 mi / 55 mph = 7.27 hr

So it took Beth 7.27 hrs; from 9 am, that's 4:16:12 that she arrives.

4:42 - 4:16:12 = 25.8 minutes = 25 minutes, 48 sec

The air that is inside a ship is much less dense than water. That's what keeps it floating! ... The closer the total density of the ship is to the density of the same volume of water, the greater the amount of the ship that will be in the water.