It has been estimated that 25% of all university students switch majors within their first two years of starting classes. If a random sample of 500 third-year students is taken at a city university, what is an estimate of the probability that 20% or less had switched majors within their first two years? Use Appendix B.1 for the z values. (Round the z value to 2 decimal places and the final answer to 4 decimal places.) Probability