Question

The total surface area of a right circular cylinder of height 9m is 440 sq. meter.Find the radius of the cylinder. (Take π = 22/7)

• A. 2.5 m
• B. 5 m
• C. 7.5 m
• D. 5.5 m

Answer 1

The correct option is B

5 m

Total surface area of right circular cylinder= 2 π r(r+h)=440$m^2$

As h=9, solving quadratic equation

2× $\frac{22}{7}$ $\times$ r (9 +r) = 440

$r^2$ + 9r - 70 = 0

$r^2$ + 14 r -5r -70 = 0

r(r +14)-5(r +14) = 0

r = 5, r = -14

Since, length can’t be negative r = 5 m