GATE Civil Engineering (CE) 2011 Solved Paper

Identical surcharges are placed at ground surface at sites X and Y, with soil conditions shown alongside and water table at ground surface. The silty clay layers at X and Y are identical. The thin sand layer at Y is continuous and free draining with a very large discharge capacity. If the primary consolidation at X is estimated to complete in 36 months, What would be the corresponding time for completion of primary consolidation at Y?