RRB Technician Grade 3 previous year question
A hollow cylindrical pipe has an external radius of 7 cm, internal radius of 6 cm, and height of 20 cm. Find the total surface area of the pipe (both ends included). (Use π = 22/7)
Asked in RRB Technician Grade 3 (10 Mar 2026 Shift 1) · Quantitative Aptitude
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Correct answer: (B) 1716 cm²
Total surface area of the hollow pipe = curved surface (outer+inner) + 2 end rings = 2πh(R+r) + 2π(R²−r²) = 2×(22/7)×20×13 + 2×(22/7)×13 = 1144 + 572 = 1716 cm².
हिंदी में प्रश्न
किसी खोखले बेलनाकार पाइप की बाह्य त्रिज्या 7 cm, आंतरिक त्रिज्या 6 cm और ऊंचाई 20 cm है। पाइप का संपूर्ण पृष्ठीय क्षेत्रफल (दोनों सिरे शामिल करते हुए) ज्ञात कीजिए। (π = 22/7 का उपयोग कीजिए)
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
उत्तर और व्याख्या देखें
सही उत्तर: (B) 1716 cm²
खोखली नली का कुल पृष्ठीय क्षेत्रफल = वक्र सतह (बाहरी+आंतरिक) + 2 सिरों के छल्ले = 2πh(R+r) + 2π(R²−r²) = 1144 + 572 = 1716 वर्ग सेमी होता है।
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