Tommy gets a 17 or a multiple of 3

Question

Tommy is using his calculator to obtain a random number from 15-25. Find the probability as a simplified fraction

Answer 1

This depends on how Tommy USES the Calculator, which has not been specified.

 

If the outputs are always in the interval [15,25] AND THEY ARE ALWAYS AN INTEGER, one could suppose that the numbers 15, 18, 21, 24 and 17 (with equal probabilities) define event E, and the sample space S contains exactly eleven equally probable outcomes, so then, UNDER THESE EXPLICIT CONDITIONS, P(E) = 5/11.

 

Without these conditions, the problem is not a good one.