In a study to detect extracellular fluid volume, 10 gm mannitol was injected by intravenous route and after waiting for adequate time for equilibration of levels, concentration was measured as 50 mg/100 ml. In this time, 10% mannitol was excreted. What is the calculated volume of ECF?
10 Litres 18 Litres 42 Litres 52 Litres