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  Logic

Catching the Bus		  
Q Every morning when Aldo, Brenda, and Cory line up at the bus stop, they can choose between two busses — one yellow and one blue.
  1. Whenever Aldo takes the yellow bus, Brenda and Cory take the same bus as each other.
  2. If Brenda takes the yellow bus, Aldo and Cory take different busses from each other.
  3. If Cory takes the blue bus, Aldo takes the same bus as Brenda.

Which of the three kids always takes the same bus? What color is it?


  
A Aldo always takes the blue bus.

STRATEGY: Make a table that shows the choices for Aldo. He can either take yellow or blue. If he takes yellow, there are two options for Brenda and Cory. If he takes blue, there are four choices for Brenda and Cory.

  Aldo Brenda Cory
A yellow yellow yellow
B yellow blue blue
C blue blue blue
D blue yellow yellow
E blue yellow blue
F blue blue yellow

Now go back to the information in the problem and eliminate the impossible cases. Number 2 makes case A and E impossible, so cross them out. Number 3 makes case B impossible, so cross that out. That leaves only cases D and F. Aldo takes the blue bus in both.