Mean proportion of 1.2 and 4.8 is …………………A) 2.4 B) 4.2�

1.	Mean proportion of 1.2 and 4.8 is …………………A) 2.4 B) 4.2 C) 3.2 D) 4.1
Answer» 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. Correct option is A) 2.4

Mean proportion of 1.2 and 4.8 is …………………A) 2.4 B) 4.2 C) 3.2 D) 4.1

Answer»

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.

Correct option is A) 2.4