Gujarati
Hindi
4.Average
hard

What is the age of a class teacher?

$I.$ There are $11$ students in the class.

$II.$ The average age of the students and the teacher is $14$ years.

$III.$ The average age of the teacher and the students is $3$ years more than that of the students.

A

Both $I$ and $III$

B

Both $I$ and $II$

C

$II$ and either $I$ or $III$

D

All  $I,$ $II$ and $III$ 

Solution

From $I.$ There are $11$ students in the class.

From $II.$ The average age of students and class teacher is $14$ years.

From $III.$ The average age of class teacher is $3$ years more than that of students.

Now, combining all three statements,

we have Average age of (students $+$ teacher) $=14 \times 12=168$ years

Average age of $11$ students $=14-3=11$ years

Total age of $11$ students $=11 \times 11=121$ years

Teacher's age $=168-121=47$ years.

Standard 13
Quantitative Aptitude

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