# Six Subway Lines

Question: SkyFi city is served by 6 subway lines - A, E, I, O, U and Z.   When it snows, morning service on line E is delayed.   When it rains or snows, service on the lines A, U and Z is delayed both morning and afternoon.

* When the temperature drops below 20 C, afternoon service is cancelled on either line A or line O, but not both.

* When the temperature rises above 40 C, afternoon service is cancelled on either line I or line Z, but not both.

* When service on line A is delayed or cancelled, service on line I is also delayed.

* When service on line Z is delayed or cancelled, service on line E is also delayed.

On February 10, it snows all day with the temperature at 18C. On how many lines service will be delayed or cancelled, including both morning and afternoon?

Answer:

The service will be delayed or cancelled on 5 lines - A, E, I, U and Z except line O.

Go through each statement and cross the subway line with delayed or cancelled service.

It is given that it snows all day with the temperature at 18C.

From (1), line E is delayed.

From (2), line A, U and Z are delayed.

From (3), either line A or line O is cancelled.

From (5), line I is delayed because of line A delay.

From (6), line E is delayed because of line Z delay.

As service on line A is delayed, service on line O can not be. Hence, service will be delayed or cancelled on 5 lines - A, E, I, U and Z except line O.

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