A radio can tune to any station in 6MHz to 10MHz band. The value of...

Given: Frequency ${f}_{1} = 6MHz$

Frequency ${f}_{2} = 10MHz$

Wavelength can be calculated using $\lambda = \dfrac{c}{f}$.

$⇒ {\lambda}_{1} = \dfrac{c}{{f}_{1}} = \dfrac{3 \times {10}^{8}}{6 \times {10}^{6}} = 50m$

$⇒ {\lambda}_{2} = \dfrac{c}{{f}_{2}} = \dfrac{3 \times {10}^{8}}{10 \times {10}^{6}} = 30m$

Wavelength bandwidth is the difference of upper lower wavelengths $= {\lambda}_{1} - {\lambda}_{2} = 20m$