Given Expression = (.53)³ - (.42)³- 3 x .58 x .42 x (.58-.42)= a³-b³ -3ab(a - b) = (a - b)³(where a = .58 and b=.42)= (.58 - .42 )³ = .16 x .16 x .16 = 0.004096
Converting each of the given fractions into decimal form, we get,5/6 = 0.838/15 = 0.532/3 = 0.663/4 = 0.754/5 = 0.86/7 = 0.85Clearly, 0.85 does not lie between 0.83 and 0.53Hence the required fraction is 6/7.