The average weight of a certain number of student in a group was 72 kg.
एक समूह में कुछ छात्रों का औसत वजन 72 kg था। यदि प्रत्येक 76 kg औसत वजन वाले 11 छात्र समूह छोड़ देते हैं, और प्रत्येक 79 kg औसत वजन वाले 5 छात्र,समूह शामिल हो जाते हैं तो समूह में छात्रों का औसत वजन 0.6 kg कम हो जाता है।समूह में शुरूआत में कितने छात्र थे?
Detailed Solution & Logic
21
Let initial number of students = n
Total weight initially = 72n
Weight removed = $11 \times 76 = 836. $
Weight added = $ 5 \times 79 = 395. $
New total weight = 72n - 836 + 395 = 72n - 441
New number of students= n - 11 + 5 = n - 6
New average = 72 - 0.6 = 71.4
$ \frac{72n - 441}{,n - 6,} = 71.4 $
72n - 441 = 71.4(n - 6) = 71.4n - 428.4
72n - 71.4n = -428.4 + 441
0.6n = 12.6
n = $ \frac{12.6}{0.6} = 21 $
Answer = 21
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