Multiple choice

The respective ratio of curved surface area and total surface area of a cylinder is 4:5. If the curved surface area of the cylinder is 1232cm2, What is the height? एक वेलन के वक्रपृष्ठ क्षेत्रफल और की कुल पृष्ठ क्षेत्रफल का क्रमिक अनुपात 4:5 है । यदि बेलन का वक्रपृष्ठ क्षेत्रफल 1232 सेमी2 है, तो ऊँचाई क्या है?

  1. 14 cm

  2. 28 cm

  3. 7 cm

  4. 56 cm

  5. 24 cm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given CSA/TSA = 4/5 and CSA = 1232. For a cylinder, CSA = 2πrh and TSA = 2πr(r+h). Therefore, 2πrh / 2πr(r+h) = 4/5, which simplifies to h/(r+h) = 4/5. Cross-multiplying: 5h = 4r + 4h, so h = 4r. If CSA = 1232 = 2πr(4r) = 8πr², then r = 7 cm and h = 28 cm. Answer B is correct.

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