Explanation:

Given, Diameter = 7 m, then radius (r) = 3.5 m and depth (h) = 4 m
Total area of wetted surface = Curved surface area of cylinder + Area of base of cylinder
= 2πrh + πr²
= πr(2h + r)
= 22/7 × 3.5 (2 × 4 + 3.5)
= 22 × 0.5 × 11.5 = 126.5 sq m