Some exercises about pawn endings

The following exercises are about the material of the earlier posts Elementary pawn endings I, II and III. In each problem it's white to move and the task is either to win or make a draw (you should be able to figure out which). The moves in the solution are either the only moves that do not change the result or the fastest way to win (usually the other winning lines just contain some unnecessary extra moves but ultimately require finding the same winning idea as given in the solution).