It is often necessary to "guess" about the outcome of an event in order to make a decision. Politicians study polls to guess their likelihood of winning an election. Teachers choose a particular course of study based on what they think students can comprehend. Doctors choose treatments for various diseases based on their assessment of likely results. You may have visited a casino where people play games chosen because of the belief that the likelihood of winning is good.
Contingency or Two-way tables are another way to look at data and access the probabilities. These tables can let you look at sub-sections of the group with counts and calculate the probabilities from the counts.