Question

9. An iron pipe 20 cm long has exterior diameter equal to 14 cm. If the thickness of the pipe is 1 cm, then the
whole surface of the pipe is
(a) 3068 cm2
(b) 1716 cm2
(c) 3268 cm2
(d) 3368 cm?
bowl is filled with​

Answer 1

Step-by-step explanation:

Height of pipe = 20 cm

External diameter = 25 cm

External radius = 25/2 = 12.5 cm

Internal diameter = 25 - (1 + 1)

= 23 cm

Internal radius = 23/2 = 11.5 cm

Let the external radius be R and the internal radius be r.

Total surface area of the pipe = 2πh(R + r) + 2π(R² - r²)

⇒ 2*22/7*20(12.5 + 11.5) + 2*22/7*{(12.5)² - (11.5²)

⇒ (44*480)/7 + (44*24)/7

⇒ 21120/7 + 1056/7

⇒ 22176/7

= 3168 cm²

So, the total surface area of the pipe is 3168 square cm.

Answer 2

Step-by-step explanation:

Answer 3068 cm2

hope it helps you