A box contains 300 envelopes, of which 25 contain $100 in cash, 100 contain $ 25, and 175 contain $10. An envelope may be purchased for $ 25. What is the sample space for the different amounts of money? Assign probabilities to the sample points and then find the probability that the first envelop purchased contains less than $ 100. Find the sample space and the weights of the sample points. ( type integers or simplified fractions)