Question 120

The ratio of radius of the base and the heightof solid right circular cylinderis 2 : 3. If its volume is 202. 125 cm$$^3$$, then its total surface area is: (Take $$\pi = \frac{22}{7}$$)

Solution

Let radius of cylinder = $$2x$$ and height = $$3x$$ cm

Volume of cylinder = $$\pi r^2h$$

=> $$\frac{22}{7} (2x)^2 (3x)=202.125$$

=> $$8x^3=42.875$$

=> $$x=\sqrt[3]{\frac{42.875}{8}}=\frac{3.5}{2}=\frac{7}{4}$$

Total surface area of cylinder = $$2\pi r(h+r)$$

= $$2\times\frac{22}{7}\times (2x)\times(3x+2x)$$

=> $$\frac{44}{7}\times10x^2$$

=> $$\frac{440}{7}\times\frac{49}{16}=192.5$$ $$cm^2$$

=> Ans - (A)

Share on Whatsapp Share on Whatsapp

Create a FREE account and get: