Find the radius of a sphere whose surface area is 154 cm\(^2\)?
A
7.00 cm
B
3.50 cm
C
3.00 cm
D
1.75 cm
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
Surface Area of a sphere = 4\(\pi\)r\(^2\)
S.A of a sphere = 154 = 4 x \(\frac{22}{7}\) x r\(^2\)
r\(^2\) = \(\frac{154 \times 7}{4 \times 22}\)
r\(^2\) = \(\frac{49}{4}\)
r = \(\sqrt{\frac{49}{4}}\)
r = \(\frac{7}{2}\)
r = 3.5cm.
Source: WAEC / JAMB / NECO Classroom Archive (Record #9331)