which one of the following states of field compaction of sand deposit truly represents the corrected standard penetration test value. N (corrected) = 12?

Option 2 : Medium dense 

Concept

A standard penetration test (SPT) is conducted in 3 stages having 150 mm penetration each. The number of blows for the first 150 mm is ignored and the number of blows in the last 300 mm penetration is noted and called Observed SPT number (N₀)

The observed SPT number (N₀) is corrected for

a) Overburden pressure

b) Dilatancy or Water table Correction

These Corrections are applied in sequence. It means the corrected value for overburden pressure is further corrected for dilatancy.

The final corrected SPT values of sandy soil are tabulated

∴ Standard penetration value ( N ) = 12 represents the soil is medium dense.