Ali picked 3 numbers, let L be the lowest number, M be the middle number, and H be the highest number.
"The lowest number was 11", therefore L = 11.
"The range was 13", so the difference from the highest number to the lowest number is 13, so:
H - 11 = 13
H = 24
"The median was 17", that means M has to be 17 in order to have a median of 17.
So the 3 numbers are: 11, 17, 24