Multiple choice

The average age of 39 students and the principal is 18 years. When the principal's age is excluded, the average age decreases by 1 year. What is the age of principal ? 39 छात्रों और प्रधानाचार्य की औसत उम्र 18 वर्ष है। जब प्रधानाचार्य की आयु को बाहर रखा गया है, औसत आयु में 1 वर्ष की कमी आती है तो प्रधानाचार्य की आयु क्या है ?

  1. 57 years/ वर्ष

  2. 60 years/ वर्ष

  3. 58 years/ वर्ष

  4. 48 years/ वर्ष
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A Correct answer
Explanation

Total age of 40 people = 40 × 18 = 720 years. Without principal, 39 students have average age of 17, so their total = 39 × 17 = 663 years. Principal's age = 720 - 663 = 57 years.

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