Tom’s giant cooler contains $30$ waters and $70$ Cokes. Tom blindly reaches into his cooler and randomly selects a beverage. If the beverage he selects is a water, there is a $90\%$ chance he will drink it. If it’s a Coke, there is only a $40\%$ chance he will drink it.
**Given that Tom drinks his beverage, what is the probability that it is a water?**
*Consider using a tree diagram to answer this question.*
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