LIC AAO Prelims practice question
Find the sum of the first 30 terms of the arithmetic progression 21, 28, 35, ….
From a LIC AAO Prelims Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (C) 3675
a = 21, d = 7, n = 30. Sₙ = n/2 × [2a + (n − 1)d] = 30/2 × [42 + 29 × 7] = 30/2 × 245 = 3675.
हिंदी में प्रश्न
समांतर श्रेढ़ी 21, 28, 35, … के प्रथम 30 पदों का योग ज्ञात कीजिए।
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
उत्तर और व्याख्या देखें
सही उत्तर: (C) 3675
a = 21, d = 7, n = 30। Sₙ = n/2 × [2a + (n − 1)d] = 30/2 × [42 + 29 × 7] = 30/2 × 245 = 3675।
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