সাধারণ গণিত→অধ্যায় ০৫ঃ বিচ্ছিন্ন গণিত→পরিসংখ্যান ও সম্ভাব্যতা

In a certain office, the human resources department reports that $60\%$ of the employees in the office commute over an hour on average each day, and that $25\%$ of the those employees, who commute over an hour on average each day commute by train. If an employee at the officer is selected at random, what is the probability that the employee commutes over an hour on average by train?