Multiple choice

The average of 20 boys and their teacher is 10 years. When the teacher's age is excluded, the average age decreases by 2 years, the age of teacher is ? 20 लड़कों और उनके अध्यापक की औसत उम्र 10 वर्ष है। जब अध्यापक की उम्र निकाल दी जाती है। तो औसत 2 वर्ष कम हो जाता है। तो अध्यापक की उम्र क्या है?

  1. 40 yr./वर्ष

  2. 50 yr./वर्ष

  3. 60 yr./वर्ष

  4. 70 yr./वर्ष
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total age of 21 people (20 boys + teacher) = 21 × 10 = 210 years. When teacher is excluded, average drops to 8 years (decrease of 2). Total age of 20 boys = 20 × 8 = 160 years. Therefore teacher's age = 210 - 160 = 50 years.

Keep practicing — related questions