Answers to last issue's Brain Teasers

Logic puzzle: Nine college students called Raju, Rani, Leela, Maxine, Rashid, Maya, Fathima, Ravi and John live in flats in the same three storey building, with three rooms on each floor. A room is in the West wing, one in the centre, and one in the East wing. If you look directly at the building, the left side is West and the right side is East. Each student is assigned exactly one room.
    1. Ravi does not live on the ground floor.
    2. Maya lives directly above John and directly next to Rani (who lives in the West wing).
    3. Rashid lives in the East wing and one floor higher than Maya.
    4. Maxine lives directly above Maya.
    5. Fathima lives directly above Leela. 
Can you find where each of their rooms is ?
Ans: Clues 2 and 4 together imply that one of the three wings has Maxine on the top floor, Maya on the middle floor and John on the ground floor.  Let's call this Wing X.
Clue 2 also tells us that Rani is on the same floor as Maya, and that Rani is in the West Wing.
So we have the picture:
====    ======     ====
West    Centre     East
====    ======     ====
--      Maxine     --
Rani    Maya       --
--      John       --
====    ======     ====
Clue 3 then places Rashid on the top floor of the East Wing.
Looking at Clue 5 now, we find that Fathima can be directly above Leela only if they are both are on the East Wing.
We only have to decide the top and ground floor of the West wing now. But this is easy, since according to Clue 1, Ravi does not live on the ground floor. So he must be on the top floor of West wing, leaving Raju to be the occupant of the ground floor of that wing.
Thus we finally have:
====    ======     ====
West    Centre     East
====    ======     ====
Ravi    Maxine     Rashid
Rani    Maya       Fathima
Raju    John       Leela
====    ======     ====
Time it: A long train, half a kilometre long, is about to enter a very long tunnel. The tunnel is 10 KM long. If the speed of the train is 35 KM per hour, how long will it take for the entire train to pass through the tunnel - from the front of the train entering to the end of the train leaving the tunnel?
Ans: The train takes 18 minutes. The front of the train has to initially travel 10 KM to leave the tunnel, and then a further 0.5 KM until the rear of the train has left the tunnel - thus a total of 10.5 KM. This takes 60 * (10.5 / 35) = 18 minutes.