Description for Correct answer:
Let first, second and third numbers be x, y and z, respectively.

Then, xy = 42 ...(i)

yz = 56 ...(ii)

xz = 48 ...(iii)

Multiplying Eqs. (i), (ii) and (iii), we get

\( \Large \left(xyz\right)^{2} = 42 \times 56 \times 48 \)

=> \( \Large \left(xyz\right)^{2} = 112896 \)

=> \( \Large xyx = 336 \)

Dividing Eq. (iv) by Eq. (i), we get

\( \Large \frac{xyz}{xyz} = \frac{336}{42} => z = 8 \)