Multiple choice

The average weight of 40 students in a class is 55 kg. 6 of them whose average weight is 52 kg left the class and another set of 6 students whose average weight is 42 kg, joined the class. What is the new average weight (in kg.) of the class? एक कक्षा के 40 विद्यार्थियों का औसत वजन 55 किग्रा है | यदि इनमे से 52 किग्रा औसत वजन के 6 लोग के स्थान पर 42 किग्रा औसत वजन के 6 नए लोग शामिल हो जाते है तो कक्षा का नया औसत वजन (किग्रा. में) क्या है ?

  1. 51.5

  2. 53.5

  3. 52.5

  4. 54
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total weight of 40 students = 40 × 55 = 2200 kg. Weight of 6 leaving students = 6 × 52 = 312 kg. Weight of 6 joining students = 6 × 42 = 252 kg. New total weight = 2200 - 312 + 252 = 2140 kg. New average = 2140/40 = 53.5 kg. The class size remains 40, so we just divide by 40. Options A (51.5), C (52.5), and D (54) are calculation errors.

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