The average age of 30 students is 9 years. If the age of their teacher is included, it becomes 10 years. The age of the teacher (in years) is:Options :27313540
Question
The average age of 30 students is 9 years. If the age of their teacher is included, it becomes 10 years. The age of the teacher (in years) is:
Options : 27 31 35 40
Solution
To solve this problem, we first need to find the total age of all the students. We do this by multiplying the average age of the students by the number of students.
So, 30 students * 9 years = 270 years
Next, we find the total age of all the students plus the teacher. We do this by multiplying the new average age (which includes the teacher) by the new total number of people (students + teacher).
So, 31 people * 10 years = 310 years
Finally, we subtract the total age of just the students from the total age of the students plus the teacher. This gives us the teacher's age.
So, 310 years - 270 years = 40 years
Therefore, the teacher is 40 years old.
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