There are 65,438+00 red, yellow and blue glass balls of the same size. Put them in a box, and at least four glass balls can be pulled out, so that two balls with the same color can be obtained. Answer choice c;

Analysis: regard red, yellow and blue as three drawers, and use pigeon hole principle to solve the worst situation.

Solution: Consider the worst case: If you touch three red, yellow and blue glass balls of different colors, you can touch 1 glass ball at will, and you can be sure that two of them are the same color.

Statistical definition

Under certain conditions, the experiment was repeated n times, where nA is the number of times that Event A occurred in n times. If with the gradual increase of n, the frequency nA/n gradually stabilizes around a certain value p, then the value p is called the probability of the occurrence of event A under this condition, and it is recorded as P (a) = P .. This definition is called the statistical definition of probability.

In history, Jacob Bernoulli is the first person to give a strict meaning and mathematical proof to the assertion that "when the number of experiments n increases gradually, the frequency nA is stable at its probability p".