In meter bridge experiment for measuring unknown resistance ' S ',...

Using balanced wheatstone condition in meter bridge

$\dfrac{R}{S} = \dfrac{70}{30}$

Given here, $R = 5 . 6kΩ$.

The, $\dfrac{S}{30} = \dfrac{5 . 6 \times {10}^{3}}{70}$

$S = \dfrac{3}{7} \times 5 . 6 \times {10}^{3} = 2400Ω$