A standard deck of playing cards is made up of 26 red cards and 26 black cards. Robbie obtains 5 identical decks of cards. He shuffles and deals a card and records its color. He replaces the card in the deck and repeats this process 25 times, obtaining 10 red cards and 15 black cards - only 40% red! Robbie wonders if the stack of cards has an unusually small proportion of red cards. What is the probability of obtaining a sample proportion less than or equal to 0.4