The free space inside a current carrying toroid is filled with a...

It is given that

${χ}_{m} = 2 \times {10}^{- 2}$

The permeability is ${\mu}_{r} = 1 + {χ}_{m} = 1 + 0 . 02 = 1 . 02$.

The magnetic field is $B = {\mu}_{r}{B}_{0} = 1 . 02{B}_{0}$

Hence, percentage increase in magnetic field is

$\dfrac{B - {B}_{0}}{{B}_{0}} \times 100$