In a camp, there are tents of the same shape and size. Each tent is cylindrical up to a height of 4 m and conical above it. The

diameters of the bases of the cylinder and the cone are both 10.5 m and the slant height of the conical part is 10 m.

If a total of 3861 m² canvas is used in making all the tents, then how many tents are there in the camp? [Use  ]