Correct option is (A) 2.4
Let mean proportion of 1.2 and 4.8 is x.
\(\therefore\) 1.2 : x : : x : 4.8
\(\Rightarrow\) 1.2 : x = x : 4.8
\(\Rightarrow\) \(\frac{1.2}x=\frac x{4.8}\)
\(\Rightarrow\) \(x^2=1.2\times4.8\) \(=1.2\times(1.2\times4)\)
\(\Rightarrow\) \(x^2=1.2^2\times2^2\) \(=(1.2\times2)^2\) \(=(2.4)^2\)
\(\Rightarrow\) x = 2.4
\(\therefore\) Mean proportion of 1.2 and 4.8 is 2.4.
