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B _ S Clue
ONE, THE BUS DRIVER. ON THE 1ST STOP, 5 PEOPLE GET ON. ON THE 2ND STOP, 5 PEOPLE GET OFF AND 10 (TWICE AS MANY AS AT 1ST STOP) PEOPLE GET ON. ON THE 3RD STOP, 10 PEOPLE GET OFF. SO THERE ARE (5 - 5 + 10 - 10) 0 PASSENGERS LEFT, WHICH LEAVES THE BUS DRIVER AS THE ONLY PERSON ON BOARD THE BUS LET: CAMPER 1 = C1 (1) CAMPER 2 = C2 (2) CAMPER 3 = C3 (5) CAMPER 4 = C4 (10) THIS IS HOW THEY CROSS THE BRIDGE: C1,C2 → (2) ← C2 (2) C3,C4 → (10) ← C1 (1) C1,C2 → (2) THE TIME IN BRACKETS () INDICATE THE TIME TAKEN TO CROSS THE BRIDGE. IF YOU SUM THEM UP, IT WILL ADD UP TO 17 MINUTES THERE WERE 65 PEOPLE TO BEGIN WITH. 19 PEOPLE GETTING OFF THE TRAIN CAN BE REPRESENTED BY -19, AND 17 PEOPLE GETTING ON THE TRAIN AS +17. -19 + 17 = -2, MEANING THAT THERE WAS A NET LOSS OF TWO PEOPLE. IF THERE ARE 63 PEOPLE ON THE TRAIN NOW, THAT MEANS THERE WERE 65 TO BEGIN WITH THE BIN WAS HALF FULL AT 10PM. THE SKIP STARTED WITH 1 LONELY BOTTLE. AT NOON: 1 PERSON CAME ALONG AND ADDED A BOTTLE, MAKING THE TOTAL 2 BOTTLES. AT 1PM: 2 PEOPLE CAME ALONG AND ADDED A BOTTLE EACH, MAKING THE TOTAL 2 + 2 = 4 BOTTLES. AT 2PM: 4 PEOPLE CAME ALONG AND ADDED A BOTTLE EACH, MAKING THE TOTAL 4 + 4 = 8 BOTTLES. AT 3PM: 8 PEOPLE CAME ALONG AND ADDED A BOTTLE EACH, MAKING THE TOTAL 8 + 8 = 16 BOTTLES. THEREFORE THE NUMBER OF BOTTLES IN THE BIN IS DOUBLING EVERY HOUR, AS IT WAS FULL AT 11PM, IT MUST HAVE BEEN HALF FULL AT 10PM