Which number replaces the qu...

A woman in a hot air balloon realized she was lost.
She reduced altitude and spotted a man below. She descended a bit more and shouted: 'Excuse me, can you help me? I promised a friend I would meet him an hour ago but I don't know where I am..'
The man below replied, 'You're in a hot air balloon hovering approximately 30 feet above the ground. You're between 40 and 41 degrees north latitude and between 59 and 60 degrees west longitude.'
'You must be an Engineer,' said the balloonist.
'I am,' replied the man, 'how did you know?'
'Well,' answered the balloonist, 'everything you have told me is probably technically correct, but I've no idea what to make of your information and the fact is, I'm still lost. Frankly, you've not been much help at all. If anything, you've delayed my trip by your talk.'
The man below responded, 'You must be in Management.'
'I am,' replied the balloonist, 'but how did you know?'
'Well,' said the man, 'you don't know where you are or where you're going. You have risen to where you are, due to a large quantity of hot air. You made a promise, which you've no idea how to keep, and you expect people beneath you to solve your problems. The fact is you are in exactly the same position you were in before we met, but now, somehow, it's my f**king fault.'