The probability of rain on Thanksgiving Day in Boston is 0.70. The probability of rain in Honolulu on Thanksgiving Day is 0.28. What is the probability that it rains in Boston or Honolulu on Thanksgiving Day? Make sure you only account for the scenario in which both Boston and Honolulu get rain on Thanksgiving Day once.

Question

anonymous · Answer

$$.70+.28-.70\times .28$$

anonymous · Answer

they are telling you to subtract the probability that they both get rain which is counted twice when you just add.  that is why you have to subtract the product

anonymous · Answer

this of course assumes those probabilities are independent, but i guess you are supposed to assume that raining in boston has nothing to do with raining in honolulu

anonymous · Answer

i get .784