What do you prefer Mirinda, Pepsi or Coke?
A vending machine has five switches which when operated gives Coca-Cola, Pepsi, Mirinda, Limka, 7-up depending upon the switch turned on.
The machine is such that each switch supply two different kind of drinks and each drinks is supplied through two different switches. If two switches are turned on, the common drink (if any), nullify each other and not come out at all. To get the drink one wants he has to turn on the right combination of switches, Put in the money, press the delivery button and get the drinks.
Use the following information:
1
) 1 & 3 gives 7-up and Mirinda.
2
) 1 & 2 gives Coca-Cola and Pepsi.
3
) 1 & 4 gives Limka, Coca-Cola, Mirinda and Pepsi.
Switches 1,2,3,4,5 don't supply 7-up, Limka, Coca-Cola, Mirinda and Pepsi respectively.
If x, y switches supply Coca-Cola (when switched on), find the value of .
The answer is 6.
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1 solution
Well, I believe the answer provided is incorrect, so I will offer my solution and hope that someone either changes the answer or explains where I have gotten it wrong. To solve, I created a five by five grid.
Step 1: The final clue provides information about each of the five switches, specifically what they don't provide. So put that in your grid.
Step 2: Notice that 1&3 produce 7-up. But since Switch 1 does not supply 7-Up, Switch 3 must. Likewise, 1&4 produce Mirinda, but switch 4 doesn't, so Switch 1 must. Finally, notice that 1&2 do NOT produce Mirinda, but 1 alone does, so 2 must also produce it (to cancel it out). That gives both switches for Mirinda, so fill in the rest of that column.
Step 3: Switch 1&3 only produce 7-up and Mirinda. But switch 3 does not produce Coca-Cola, so that means that switch 1 cannot either. But since 1&2 produce Coca-Cola and Pepsi, and 1 is not Coca-Cola, then 1 must be Pepsi and 2 must be Coca-Cola, and those two rows can be filled in. Also, since 1&3 do not produce Pepsi, but 1 alone does, then Pepsi must also be on Switch 3 to cancel, which means Limka is not on Switch 3.
Step 4: Now, it's just finishing it up. Limka is not on Switches 1,2, or 3. so must be on 4 and 5. 7-up is not produced with 1&4, and is not on 1, so cannot be on 4, and so must be on 5, which leaves Coca-Cola on 4. As a result, Coca-Cola is on 2 and 4, so the answer is 6.