A meta-analysis on the relation between fluid intelligence and reading/mathematics: Effects of tasks, age, and social economics status.This study aimed to determine the relations between fluid intelligence (Gf) and reading/mathematics and possible moderators.  A meta-analysis of 680 studies involving 793 independent samples and more than 370,000 participants found that Gf was moderately related to reading, r = .38, 95% CI [.36, .39], and mathematics, r = .41, 95% CI [.39, 44]. 
Meta-analysis