RRB NTPC CBT-1 previous year questionA hollow spherical shell is made of a metal of density 39 g/cm3. Its internal and external radii are 12 cm and 13 cm, respectively. What is the weight (in kg) of the shell?
A hollow spherical shell is made of a metal of density 39 g/cm3. Its internal and external radii are 12 cm and 13 cm, respectively. What is the weight (in kg) of the shell? 
Asked in RRB NTPC 2026 — 15 June Shift 3 · Quantitative Aptitude
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Correct answer: (A) 76.648
Volume of the shell = (4/3)π(R³-r³) = (4/3)×(22/7)×(13³-12³) = (4/3)×(22/7)×469 ≈ 1965.33 cm³. Weight = Volume × density = 1965.33×39 ≈ 76,648 grams = 76.648 kg.
हिंदी में प्रश्न
एक खोखला गोलीय कोश 39 gicm? घनत्व वाली धातु से बना है। इसकी आंतरिक sie are त्रिज्याएं क्रमश: 12 cm और 13 cm हैं। कोश का वजन (kg में) कितना है? (T= ---और घनत्व 5 HT उपयोग कोजिए) 
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
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सही उत्तर: (A) 73.648
कवच का आयतन = (4/3)π(R³-r³) = (4/3)×(22/7)×(13³-12³) = (4/3)×(22/7)×469 ≈ 1965.33 घन सेमी। वजन = आयतन × घनत्व = 1965.33×39 ≈ 76,648 ग्राम = 76.648 किग्रा।
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