Probability: Smart Cars, Architects, and The “Color” Black


Waiting for the bus in Roma, Italia, May 2007.  Smart Cars stopped at a stoplight.

What’s the probability of photographing 3 Smart Cars in a single (non-panoramic, fairly close) shot without being at a Smart Car dealership

In Europe that probability is as high as the probability of five architecture students independently walking into a room with each wearing a black shirt!  Which is VERY high! 

That’s what happened last summer when I studied in the Netherlands with fellow architecture and landscape architecture students.  A few of us were in the common kitchen area of our flat, and somebody pointed out that two people in the room were both wearing a black top and jeans…  I looked down, and I was wearing the same thing!  And looking around the room, another black shirt-jeans combo!  Another person entered the room…  Black top, jeans!

Hypothetically, if 5 students each had two shirts in his/her closet, a black one and a non-black one and blindly grabs one to wear, the chance that all five would wear black is (1/2)^5 or 1/32 or 3.125 %. 

Of course that’s a hypothetical situation.

If that black to non-black ratio were actually GREATER than 50% (as in the case of an architect student’s closet!), then chances are greater than 3.125 %.  (Eg, being conservative, (0.80)^5 = 32.768 %.)

So…  That strange occurence of virtually everyone in the room wearing the same black top-jeans combo is actually statistically very likely!  As is the likelihood of seeing 3 Smart Cars on the road next to each other in Rome!

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