This is a nice and simple question. Here we can assume that next year, will be somewhat related to this graph - so this is only the theoretical probability. Therefore, if we can calculate the probability with which there are more than 5 inches of rain, it will apply to the next year as well.
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Taking a look at the graph, we see that 7 out of the 10 years given to us are greater than 5 inches of rainfall. Therefore, the probability that there will be more than 5 inches of rainfall next year should be 7 / 10 ( 7 years / 10 years ), and 7 / 10 with respect to percent would be 70%. Your solution is the second option.
