a) 0.865
b) 0.872
c) 0.861
d) 0.881

Answer: c
Explanation: Given,
Porosity of 30%=0.3
voids ratio in the loosest state e_min= 0.35
voids ratio in the densest state e_max=0.92
e=\(\frac{n}{(1-n)}\)
e=\(\frac{0.3}{(1-0.3)}\)
e=0.429
I_D=\(\frac{(e_{max} – e)}{(e_{max}-e_{min})}\)
I_D=\(\frac{(0.92 –0.429)}{(0.92-0.35)}\)
I_D= 0.861.