Chapter 8.1, Problem 11MS

A card reunion—black first (S). Using a shuffled deck of cards, remove cards from the top of the deck in pairs. For each pair where the first card is black, record whether the second card is red or black. After you have gone through 10 pairs, reshuffle the deck and repeat until you have recorded 50 cases where the first card of the pair is black. What fraction of those pairs had both cards black?