RRB NTPC CBT-1 previous year question
If the mean of the following data is 40, find the missing frequency. x 10 20 30 40 50 60 frequency 2 3 1 4 f 4
Asked in RRB NTPC 2026 — 18 June Shift 2 · Quantitative Aptitude
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Correct answer: (C) 5
Total frequency = 14+f, and sum of (x times frequency) = 510+50f. Setting mean = (510+50f)/(14+f) = 40 and solving gives 510+50f = 560+40f, so 10f = 50, i.e. f = 5.
हिंदी में प्रश्न
यदि निम्नलिखित आंकड़ों का माध्य 40 है, तो लुप्त बारंबारता ज्ञात कीजिए। x — 10 20 30 40 50 60 बारंबारता 2 3 1 F ) 4
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उत्तर और व्याख्या देखें
सही उत्तर: (C) 4 ह ¥
कुल बारंबारता = 14+f, और (x गुणा बारंबारता) का योग = 510+50f। माध्य = (510+50f)/(14+f) = 40 रखकर हल करने पर 510+50f = 560+40f, अतः 10f = 50, यानी f = 5।
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