On vijay's mp3 5/6 of the 4 hours of music is rock and hip-hop. How many hours of rock and hip-hop does vijay have?

Breaking down the 4hours, we get 240mins.

5/6 * 240mins = 200mins

and that 200mins is equivalent to 3 hours 40 minutes.

therefore vijay have just 3:40 hours of rock and hip hop.