Multiple choice

In an examination the average of class “A” was found to be ‘x’ marks. After deducting a computational error, the average marks of 100 candidates got reduced from 74 to 54. The average thus came down by 25 marks. The total numbers of candidates who took the exam were? एक परीक्षा में कक्षा "A" का औसत अंक 'x ' पाया गया। एक कम्प्यूटेशनल त्रुटि को कम करने के बाद, 100 उम्मीदवारों के औसत अंक 74 से घटकर 54 हो गए। इस प्रकार औसत में 25 अंको की कमी आई । परीक्षा देने वाले उम्मीदवारों की कुल संख्या थी?

  1. 50

  2. 20

  3. 80

  4. 70

  5. 60
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total candidates = n. Original average = x. Total marks = nx. After error correction: 100 candidates' marks changed from 74 to 54. New total = nx - 100(74-54) = nx - 2000. New average = x - 25. So (nx - 2000)/n = x - 25. This gives: nx - 2000 = nx - 25n. Thus 25n = 2000, n = 80.

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