Okay this is very simple
The length of the longest lead is 1 3/4
The length of the shortest lead was 1/4
The difference between the longest lead and the shortest lead is 1 1/2
The length the most students had was 1/2
The of the sum of the two shortest lengths are 3/4
The difference of the longest lead and the second shortest lead is 1 1/4
hope this helps :)