Elementary School Entrance Exam Question

[igorlord]

"What number does ? stand for on the last line?"
(taken from here)

8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9312 = 1
0000 = 4
2222 = 0
3333 = 0
5555 = 0
8193 = 3
8096 = 5
7777 = 0
9999 = 4
7756 = 1
6855 = 3
9881 = 5
5531 = 0
2581 = ?

Hint (read ONLY if you are stuck!): An "average" preschooler will likely have a much easier time

Comments

[zachtogerasim]

statistically, it should be 2

[igorlord]

:) This is very interesting. Could you elaborate on the application of statistics to this problem? :)

[zachtogerasim]

among the answers, we have nine 0s, two 1s, one 2, two 3s, three 4s, two 5s and one 6
if you plot this, you will see that the only way to make the curve smoother is to answer 2 :-)

[igorlord]

Intriguing! What curve were you trying to fit over the data? Probably a picture of a "before" and "after" curve would serve as a decent illustration? :) :)

[zachtogerasim]

exactly