Vijay's sister miranda says 15/18 of the 4 hours of music is rock and hip-hop. is she correct? explain how you know?

First, convert 1 1/4 into an improper fraction which is 5/4
Then, convert 5/4 making sure that the denominator is 8 in order to compare it with 5/8. (5/4 = 10/8)
Since you now know that 5/4 is equal to 10/8, now you can compare and see how much bigger 10/8 is than 5/8. 
10/8 - 5/8 = 5/8

So, 1 1/4 is 5/8 greater than 5/8