Question on: JAMB Mathematics - 2009

Surface area of a sphere = 4(\pi)r²

4(\pi)r² = 154 cm²

(\pi)r² = (\frac{154}{4})

= 38.5

(\pi)r² = 38.5

r² = 38.5 + (\frac{22}{7}) (\to) r² = 38.5 x (\frac{7}{22})

r² 12.25 (\to) r = (\sqrt{12.25})

= 3.5 cm