The average age of 30 boys of a class is equal to 14 years. When the age of…
2023
The average age of 30 boys of a class is equal to 14 years. When the age of the class teacher is included the average becomes 15 years. Find the age of the class teacher?
Answer: A. 45 — Answer: 45 years Explanation: Total age of the 30 boys = 14 × 30 = 420 years. Total age when the teacher is included = 15 × 31 = 465 years. Age of the teacher…
- A.
45
- B.
42
- C.
50
- D.
44
Attempted by 192 students.
Show answer & explanation
Correct answer: A
Answer: 45 years
Explanation:
Total age of the 30 boys = 14 × 30 = 420 years.
Total age when the teacher is included = 15 × 31 = 465 years.
Age of the teacher = 465 − 420 = 45 years.
Shortcut formula: teacher's age = new average × (n + 1) − old average × n = 15 × 31 − 14 × 30 = 45.
Therefore, the age of the class teacher is 45 years.
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