Question 86Asked in BPSC TRE 1.0 (2023) Mathematics Class 11-12

Which term of the progression 5, √5, 1, ... is 1/625?श्रेढ़ी 5, √5, 1, ... का कौन-सा पद 1/625 है?

श्रेढ़ी 5, √5, 1, ... का कौन-सा पद 1/625 है?
  1. A10th10वाँ
  2. B11th11वाँ
  3. C12th12वाँ
  4. DMore than one of the aboveउपर्युक्त में से एक से अधिक
  5. ENone of the aboveउपर्युक्त में से कोई नहीं
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Correct answer: (B) 11th11वाँ

Explanation

This is a GP with a = 5 and r = 1/√5, so the nth term is 5·5^(−(n−1)/2) = 5^(−4). So 1 − (n − 1)/2 = −4, which gives n − 1 = 10 and n = 11.यह a = 5 और r = 1/√5 वाली गुणोत्तर श्रेढ़ी है, इसलिए nवाँ पद 5·5^(−(n−1)/2) = 5^(−4)। अतः 1 − (n − 1)/2 = −4, जिससे n − 1 = 10 और n = 11।

From BPSC TRE 1.0 (2023) Mathematics Class 11-12 — Previous Year Paper

This is question 86 of BPSC TRE 1.0 (2023) Mathematics Class 11-12 — Previous Year Paper. See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.