Analysis / Improbably Low IQ

To illustrate exactly how improbable a given IQ testing, go score might be, see the following table of statistics on below average IQs. Scores are from the Stanford-Binet test, the original and best-known IQ test — see here. They follow a normal (bell curve) distribution with a mean of 100 points and a standard deviation of 15 points.
IQ Occurrence Frequency On Earth (of 7 000 000 000)
≤10050% 1 in              2 3 500 000 000
≤ 9537% 1 in              3 2 586 089 381
≤ 9025% 1 in              4 1 767 447 763
≤ 8516% 1 in              6 1 110 586 778
≤ 8009.1% 1 in             11 638 478 538
≤ 7504.8% 1 in             21 334 532 466
≤ 7002.3% 1 in             44 159 250 924
≤ 6500.98% 1 in            102 68 707 300
≤ 6000.38% 1 in            261 26 812 664
≤ 5500.13% 1 in            741 9 449 286
≤ 5000.043% 1 in          2 331 3 003 422
≤ 4500.012% 1 in          8 139 860 065
≤ 4000.003 2% 1 in         31 574 221 699
≤ 3500.000 73% 1 in        136 176 51 404
≤ 3000.000 15% 1 in        653 327 10 714
≤ 2500.000 029% 1 in      3 488 556 2 007
≤ 2000.000 004 8% 1 in     20 741 279 337
≤ 1500.000 000 73% 1 in    137 360 561 51
≤ 1000.000 000 10% 1 in  1 013 594 635 7
≤  500.000 000 012% 1 in  8 336 093 696 1
≤  000.000 000 001 3% 1 in 76 429 353 031 0
http://tvtropes.org/pmwiki/pmwiki.php/Analysis/ImprobablyLowIQ