Question

Air is pumped into the balloon so that it's radius doubles every 10 seconds using 3.14 as an approximation for pie , find its surface area after 30 seconds round to the nearest tenth

Answer 1

Explanation:

Let the balloon be a sphere and surface area = ⁴/₃πR³

After 30 seconds, radius will be 4R

Let R= 1cm, After 30 seconds R = 4 cm

Hence surface area = ⁴/₃π(4R)³ = 26794667R³ = 1071.7867 cm² ≅ 1070 cm²