In the article, we prove that λ1=1/2+[(2+log(1+2))/2]1/ν−1/2, μ1=1/2+6ν/(12ν), λ2=1/2+[(π+2)/4]1/ν−1/2 and μ2=1/2+3ν/(6ν) are the best possible parameters on the interval [1 / 2 , 1] such that the double inequalities Cν[λ1x+(1−λ1)y,λ1y+(1−λ1)x]A1−ν(x,y)<RQA(x,y)<Cν[μ1x+(1−μ1)y,μ1y+(1−μ1)x]A1−ν(x,y),Cν[λ2x+(1−λ2)y,λ2y+(1−λ2)x]A1−ν(x,y)<RAQ(x,y)<Cν[μ2x+(1−μ2)y,μ2y+(1−μ2)x]A1−ν(x,y) hold for all x, y> 0 with x≠ y and ν∈ [1 / 2 , ∞) , where A(x, y) is the arithmetic mean, C(x, y) i...