Delhi Police Constable practice question
The mean of 38 observations was found to be 78. Later it was discovered that an observation 100 was wrongly read as 43. Find the correct mean.
From a Delhi Police Constable Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (C) 79.5
Wrong sum = 38 × 78 = 2964. Correct sum = 2964 − 43 + 100 = 3021. Correct mean = 3021/38 = 79.5. (Shortcut: correct mean = 78 + (100 − 43)/38.)
हिंदी में प्रश्न
38 प्रेक्षणों का माध्य 78 पाया गया। बाद में पता चला कि एक प्रेक्षण 100 को गलती से 43 पढ़ लिया गया था। सही माध्य ज्ञात कीजिए।
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सही उत्तर: (C) 79.5
गलत योग = 38 × 78 = 2964। सही योग = 2964 − 43 + 100 = 3021। सही माध्य = 3021/38 = 79.5। (शॉर्टकट: सही माध्य = 78 + (100 − 43)/38।)
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