[A true story] A local grocery store ran a promotional game in which they give out game cards with 8 covered spots. Three of the spots (when uncovered!) said "STOP," and the other five spots contained food and money prizes, only two of which matched, for instance STOP, $5, macaroni, STOP, $1, macaroni, $10, STOP. To play the game, you rubbed off the spots in any order you like, revealing what's underneath ("STOP" or a prize). If you uncovered two spots with the same prize before uncovering a "STOP," you won that prize (so there was only one winning prize per card, but, on every card, you could win that prize if you uncovered the spots in the right order). The back of the card said that "based on probability," the odds of any one card winning are 1 in 10. Explain why this is correct.