150 times
out of the first 5 cards, there is a 3/5 chance of drawing a yellow.
if you replace the card and draw again, you still have a 3/5 chance of drawing a yellow card.
keep doing this process for 250 draws, each draw will always have 3/5 chance of drawing a yellow card.
so 3/5 +3/5 +3/5 +... (250 times) = 250 x 3/5 = 150