1. ## Conditional Probability

Mr B is a teacher at a high school, who is occasionally late for this classes.
Mr B teaches two subjects, Chemistry and Physics. It is known that he's late 10% of the time for Chemistry and 15% of the time for Physics. Rumors from student said that Mr B was late again.. What is the probability this is rumor came from a Chemistry student. Assuming that 75% are doing Chemistry and 25% are doing Physics. (Note: no students take both subjects)

2. Originally Posted by shiiganB
Mr B is a teacher at a high school, who is occasionally late for this classes.
Mr B teaches two subjects, Chemistry and Physics. It is known that he's late 10% of the time for Chemistry and 15% of the time for Physics. Rumors from student said that Mr B was late again.. What is the probability this is rumor came from a Chemistry student. Assuming that 75% are doing Chemistry and 25% are doing Physics. (Note: no students take both subjects)
Draw a tree diagram and then apply Bayes Theorem. If you need more help, please show your working and say where you're stuck.

(You will find plenty of questions like this one if you search this subforum - using the Search tool might help).