Question
Download Solution PDFThe average age of 35 students in a group is 15 years. When the teacher's age is included, the average age of the group increases by 1.25 years. What is the teacher's age (in years)?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
Average age of 35 students = 15 years
Number of students = 35
Average age increases by = 1.25 years
Formula used:
New average = (Sum of ages of group + Teacher's age) ÷ Total members
Sum of ages of group = Average × Number of members
Calculation:
Sum of ages of 35 students = 15 × 35 = 525
New average = 15 + 1.25 = 16.25
New total members = 35 + 1 = 36
New total age = New average × Total members
⇒ New total age = 16.25 × 36 = 585
Teacher's age = New total age - Sum of ages of students
⇒ Teacher's age = 585 - 525 = 60
∴ The correct answer is option (2).
Last updated on Jul 8, 2025
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