the mean age of 10 students of a class is 15 years A student of age 14 years leaves - Maths - Probability

Question

the mean age of 10 students of a class is 15 years A student of
age 14 years leaves the class and in his place age of their teacher
is counted This increased the mean age of group to 16 years Find
the age of the teacher

Rayya Halim · Accepted Answer

The mean age of 10 students of class is 15 yrs.Let x is the total of the ages of 10 students.

Therefore

$\frac{x}{10} = 15 \Rightarrow x = 15 \times 10 = 150$

Now a 14 yr student leaves and age of teacher is counted and mean becomes 16 years. Let age of teacher be y

Therefore

$\frac{x - 14 + y}{10} = 16 \Rightarrow 150 - 14 + y = 160 \Rightarrow y = 160 - 150 + 14 \Rightarrow y = 24 y e a r s$

the mean age of 10 students of a class is 15 years. A student of age 14 years leaves the class and in his place age of their teacher is counted. This increased the mean age of group to 16 years. Find the age of the teacher.