Mean proportion of 1.2 and 4.8 is …………………

A) 2.4 

B) 4.2 

C) 3.2 

D) 4.1

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2 Answers

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.

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Correct option is  A) 2.4

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