Q:

You have four socks in your drawer, 2 blue and 2 brown. You get up early in the morning while it's dark, reach into your drawer, and grab two socks without looking. What is the probability that the socks are the same color? (Hint: If you take one sock first, what's the probability the second sock matches it?) If instead there are 13 blue and 13 brown socks, what is the probability that the socks you choose are the same color? (please write as a fraction.) first case ____________second case _____________

Accepted Solution

A:
Answer:First Case: 1/3Second Case: 12/25Step-by-step explanation:The first caseNumber of Blue Socks: 2Number of Brown Socks: 2Note that the first sock is guaranteed to be of the same color as those chosen. It is the only second sock that has to match the color of the first sockProbability of picking socks of same colour = Probability of picking 2 blue socks or Probability of 2 brown socksMathematically,P(Same Color) = P(Blue Socks) * P(Brown Socks)P(Blue Socks) = P(1st blue socks) * P(2nd blue socks)P(Blue Socks) = 2/4 * 1/3 = 1/6P(Brown Socks) = P(1st brown socks) * P(2nd brown socks)P(Brown Socks) = 2/4 * 1/3 = 1/6P(Same Color) = P(Blue Socks) * P(Brown Socks)P(Same Color) = 1/6 + 1/6P(Same Color) = 1/3The second caseNumber of Blue Socks: 13Number of Brown Socks: 13Note that the first sock is guaranteed to be of the same color as those chosen. It is the only second sock that has to match the color of the first sockProbability of picking socks of same colour = Probability of picking 2 blue socks or Probability of 2 brown socksMathematically,P(Same Color) = P(Blue Socks) * P(Brown Socks)P(Blue Socks) = P(1st blue socks) * P(2nd blue socks)P(Blue Socks) = 13/26 " 12/25 = 6/25P(Brown Socks) = P(1st brown socks) * P(2nd brown socks)P(Brown Socks) = 13/26 " 12/25 = 6/25P(Same Color) = P(Blue Socks) * P(Brown Socks)P(Same Color) = 6/25 + 6/25P(Same Color) = 12/25