Answer to Question #21933 in Statistics and Probability for jamer binuya
Sample space for the different amount of money is 3, because there are 3 possible variants of envelopes.
If only 2 envelopes are chosen then the sample space consists of pairs (a, b), where a, b belong to one of three types of envelopes (500 php, 250 php, 100 php). The probability of the sum of both to be under 100 php is zero because the value of each envelope is greater than or equal to 100 php.
What if someone were to pick 2 envelopes. What would be the probability of the sum of both to be under 100$?