In a row in East-West direction, Dipika is on 11th position from West and Sudesh is on 15th position from East end. If they exchange their positions, Sudesh will be on 9th position from East end. How many persons are there in the row?

According to question,we have
Dipika's position = 11th from West
Sudesh's position = 15th from East end.
After interchanging their positions ,
Sudesh's current position = 9th from East end.
∴ Total number of persons in the row = Dipika's position + Sudesh's current position - 1
Total number of persons in the row = 11 + 9 – 1
Hence ,total number of persons in the row = 20 – 1 = 19