To calculate the length of tarpaulin required to make a conical tent of height 8m and base radius 6m, we can use the formula for the curved surface area of a cone, which is πrl, where r is the base radius and l is the slant height.

Here are the steps to solve the problem:

1. Calculate the slant height of the cone using the Pythagorean theorem: l = √(r^2 + h^2) = √(6^2 + 8^2) = 10m.

2. Calculate the curved surface area of the cone using the formula: πrl = 3.14 x 6m x 10m = 188.4m^2.

3. Divide the area by the width of the tarpaulin to get the length: 188.4m^2 ÷ 3m = 62.8m.

4. Add the extra length of material required for stitching margins and wastage, which is 20cm or 0.2m, to get the actual length required: 62.8m + 0.2m = 63m.

Therefore, the required length of tarpaulin 3m wide to make a conical tent of height 8m and base radius 6m is 63m.