Wow ! This is one that I had to think about overnight, and it's one
that I'll carry with me to fascinate other people with.
Here's how I finally decided to approach it:
-- Walking up the escalator when it's not operating, she climbs
1/25 = 0.04 of the total height each second.
-- When it's operating and she's standing on it, the step that she's
standing on climbs 1/16 = 0.0625 of the total height each second.
-- When it's operating AND she's walking, she climbs (0.04 + 0.0625) =
0.1025 of the total height each second.
0.1025 height per second = 1 / 0.1025 = 9.756 seconds per height.
