Let 'σ'be conductivity, and'μ' be mobility,

RHbe hall coefficient, 'ρ' be resistivity,

'n' be no. of electrons and 'e' be charge of electron.

(σ = neμ)

or

(μ=\dfrac{1}{ne}. σ)

(∴μ=R_H σ)

For resistivity,

(ρ= \dfrac{R_H}{μ})

We know,

$R_H=2.25\times10^{-5}$m3/C

(μ=0.025)m2/V-sec

thus,

(ρ=\dfrac{2.25\times10^{-5}}{0.025})

(∴ρ=9\times10^{-4})ohm-m

resistivity of P-type silicon is $9\times10^{-4} $ohm-m