Subject: General Aptitude · Chapter: Average · Exam: · Marks: · Difficulty:
The average age of a class of 39 students is 15 years. If the age of the teacher be included, then the average increases by 3 months. Find the age of the teacher.
Answer
Answer (as printed):
Explanation
Total age of 39 persons = (39 × 15) years = 585 years. Average age of 40 persons = 15 years 3 months = $\frac{61}{4}$ years. Total age of 40 persons $=\left(\frac{61}{4} \times 40\right)$ years $=610$ years. ∴ Age of the teacher $=(610-585)$ years $=25$ years.
Explanation as extracted from the printed page; notation may be imperfect.