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- Write average and count.
- Find total = average x count.
- Adjust total if values are added/removed/replaced.
Correct Answer: C
Correct Answer: C
Method / Topic: Average
The answer follows from total divided by number of values.
Short Explanation
Detailed Explanation
Correct Answer: C
Method / Topic: Average
Total age of 8 students = 8 × 15 = 120 years. After including the teacher, there are 9 people and the average is 18. New total = 9 × 18 = 162 years. Teacher's age = 162 - 120 = 42 years.
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Learn + Solve: Shortcut, Trap & Fast Route Click to view shortcut, steps, and common mistake
Shortcut used, common trap, and the fastest solving route
- Write average and count.
- Find total = average x count.
- Adjust total if values are added/removed/replaced.
The average age of 8 students is 15 years. If the teacher's age is included, the average becomes 18 years. What is the teacher's age?
Explanation
Correct Answer: C
Method / Topic: Average
The answer follows from total divided by number of values.
Short Explanation
Detailed Explanation
Correct Answer: C
Method / Topic: Average
Total age of 8 students = 8 × 15 = 120 years. After including the teacher, there are 9 people and the average is 18. New total = 9 × 18 = 162 years. Teacher's age = 162 - 120 = 42 years.
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