SBI Clerk Prelims practice question
A wedding hall arranges chairs in concentric rows around a stage, and the count of chairs in the first five rows is 2, 8, 18, 32 and 50 respectively (each row's count being twice a perfect square of its row number). How many chairs will the sixth row have?
From a SBI Clerk Prelims Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (D) 72 chairs
Each row's chair count equals 2 x (row number)2: row1=2x1=2, row2=2x4=8, row3=2x9=18, row4=2x16=32, row5=2x25=50. So row 6 = 2 x 36 = 72 chairs.
हिंदी में प्रश्न
एक शादी के हॉल में मंच के चारों ओर संकेंद्रित पंक्तियों में कुर्सियाँ लगाई गई हैं, और पहली पाँच पंक्तियों में कुर्सियों की संख्या क्रमशः 2, 8, 18, 32 और 50 है (प्रत्येक पंक्ति की संख्या उसकी पंक्ति संख्या के वर्ग का दोगुना है)। छठी पंक्ति में कितनी कुर्सियाँ होंगी?
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सही उत्तर: (D) 72 कुर्सियाँ
प्रत्येक पंक्ति की कुर्सी संख्या 2 x (पंक्ति संख्या)2 के बराबर है: पंक्ति1=2x1=2, पंक्ति2=2x4=8, पंक्ति3=2x9=18, पंक्ति4=2x16=32, पंक्ति5=2x25=50। इसलिए पंक्ति 6 = 2 x 36 = 72 कुर्सियाँ।
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