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# Ships passing in the night

## Question

Every day at noon a ship leaves New York for London, and at that moment a ship also leaves London for New York. It's a leisurely trip that takes seven days and seven nights. How many London-bound ships will the ship leaving London today meet during its trip to New York?

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15 ships.

It takes 7 days and 7 nights for a ship to reach Newyork to London and from London to Newyork.
Each day at Noon I ship leaves Newyork. So today when a ship X leaves London, 7 ships are already in the sea including a ship touching London.
The ship X will take 7 days and 7 nights to reach Newyork, so by the time X touches Newyork

7 more ships will sail into the sea, and eighth ship will be leaving Newyork.

Therefore, X will meet 7 + 8 ships during its course of journey.

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If the earth is stationary reference ,then
Sun rotates clockwise: 15 deg/hr
London-NewYork span: 74deg

for NewYork bound ships: 74deg/7=15T-360
Noon again at T=24.7047619 hrs
for London bound ship: 74deg/7=360-15T
Sunrise again at T = 23.2952381 hrs

London bound should arrive earlier

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