Question

If $\frac{5}{3x}$ = $\frac{25}{27}$, prove that x lies between 1 and 2.

Answer 1

$\frac{5}{3x}$ = $\frac{25}{27}$

By cross multiplication, we get

$5\times 27=3x\times 25$ (0.5 mark)

$\Rightarrow 3x=\frac{5\times 27}{25}$

$\Rightarrow x=\frac{5\times 27}{3\times 25}$

$\Rightarrow x=\frac{9}{5}$ (1 mark)

$=1.8$, which lies between 1 and 2. (0.5 mark)
Hence proved.