I travel to work by route A or route B. The probability that I choose route A is 1/4.The

probability that I am late for work if via route A is 2/3 and the corresponding probability if I

go via route B is 1/3 .

A. What is the probability that I am late for work on Monday?

B. Given that I am late for work, what is the probability that I went via route B.

PS.How to approach such questions??