Explanation:
the surface area is the sum of the ground circle area (the top is left open) and the area of the curved mantle.
the area of the circle is
pi×r² = 22/7 × 5² = 25×22/7 = 550/7 cm² =
= 78.57142857... cm²
the area of the curved mantle is
2×pi×r × height = 2×22/7 × 5 × 12 = 2640/7 cm² =
= 377.1428571... cm²
the total surface area is the sum :
550/7 + 2640/7 = 3190/7 = 455.7142857... cm²