Here, l = 4 m, b = 3 m, h = 2.5 m
The tarpaulin is needed to cover 5 faces only (excluding the floor)
Surface area of the shelter = lb + 2 (bh + hl)
= 4 × 3 m2 + 2(3 × 2.5 + 2.5 × 4) m2
= 12 m2 + 2(7.5 + 10) m2 = (12 + 35) m2 = 47 m2
Hence, 47 m2 of tarpaulin is required to make the shelter Ans.