Here is data from the Cognitive Abilities Test for UK students in 2009/10 via Ambiguous.
Some interesting things to take away here:
(1) The sample is very large. Verbal IQ has the highest correlation with academic performance in most subjects, followed by Quantitative IQ, and then Non-Verbal Reasoning (recognizing patterns and such, I imagine).
(2) Indians do almost as well as Whites, although the structure of their cognitive abilities are a bit different: About 4 points lower than Whites in Verbal, but almost 2 points better in Quantitative. As rec1man said, “The Patels and Sikhs are Upper-Shudra / Vaishya and this is 80% of the diaspora in UK.” So this is highly encouraging for India’s eventual prospects; in indicates that the broad middle can in principle build a reasonably wealthy, middle-class society.
(3) The Pakistanis and Bangladeshis also don’t do too badly – certainly better than I would have expected (I visited a Pakistani school once in the UK and it was horrific).
(4) This might imply we are actually looking at the following average-IQ groups in India: Lower 40% – 93; Middle 40% – 99; Top 20% – 105, for an overall average of 98 (once Flynn Effect is done with them). That’s better than Greece today and certainly good enough to have a developed society. But there’s tons of challenges: Malnutrition, slums, poor education, widespread vegetarianism (both voluntary and involuntary – due to poverty) that have to be sorted out for India to perform to its potential.