# Sunday Probability Puzzler

The Sock Drawer Probabilities, likelihoods, odds ratios, etc. All of these things are important when deciding on public health and medical interventions. In light of this, we present you with our first probability puzzler.

You have a sock drawer with red socks and white socks. You want the probability of drawing two red socks, in the dark, to be 1/2. What is the minimum number of white and red socks in the drawer such that the probability is 0.50?

No cheating. Show your work and explain. Winner gets to pick the next 60s dish.

### 6 Responses to Sunday Probability Puzzler

1. Nancy Lerner

2 red 2 white

• Sorry, sis, but it’s wrong. If you have 2 red socks and 2 white socks in the drawer at the first grab, your chances of grabbing a red sock are 2/(2+2)= 0.5
At the second grab, your chances would be 1/(1+2),or 0.3333. Since the probability of two events occurring in succession is the product of their probabilities, the answer would be 0.333 x 0.5= 0.167. So with 2 white and 2 red socks in the drawer, your chances of picking two red socks is only 1 out of 6.

2. elizabeth

Three red, one white. First pick .75, second pick .6667.

3. Nancy Lerner

Ohhhh. Been a while. It is coming back to me, sort of.

4. Gancarski, Joan (DPH)

I thought you were a Cubs fan; thus you would not be selecting Red Sox nor White Sox.

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