Radio brain teaser

I just asked this question on the air, so for those of you who didn't figure it out or who didn't hear the question, here it is again, followed by the down a bit for the answer. A hot drink vending machine has 3 buttons: Coffee, Tea, and Random (gives either coffee or tea). But the machine has been wired incorrectly so that no button is labeled correctly. It costs 50 cents to get a drink from the machine. What's the minimum amount of money you need to put in the machine to figure out what each button does? . . . . . . Answer below... . . . . . . . . . . . . . . . . You only need to put in 50 cents, and then hit the "Random" button. It will give you either tea or coffee, so you'll know that the Random button is then either the tea or coffee button. Let's say it's tea (and you can reverse the arguments if it's coffee). Then since the other two buttons must also be wrong, it means the coffee button can not be coffee so the tea button must be coffee and the remaining coffee button must be the random button.
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