Math.floor(math.random)?

Need some help on how to use math.floor(math.random) on a movieclip…

Basically i have 2 movieclip called apple and orange.

apple and orange will move out from the right of the stage to the left of stage. the ending part of the stage is at the 3/4 mark and it will disappear.
The disappearing part i have already solved it but not the appearing at different speed part…

how do you like use the above method <Math.floor(math.random)> to make the apple and orange appear at different timing?? (if u guys do not know what i meant i have a link for u. its base on a game)

i went to research on how to make random objects move at random and found math.floor(math.random)… but i do not noe how to do it…to make them move at random.

this is what i have come up with using a logic from my head.

apple.x -= math.floor(math.random(something something));

minus sign before equal sign to make it move from right to left on the x-axis but the rest of the method of math.floor and math.random i have no idea how to use it.

someone help me thx