The mean age of 30 students in a class is 14 years. 5 students with mean age of 15 years left the class. Find the mean age of remaining students

Mean age of 5 students who left $=15$

Remaining  no. of students  $=25$

Total age of left over students$=\left(30\times 14\right)-\left(5\times 15\right)$

$=420-75$

$=345$

Mean of remaining 25 students $=\frac{345}{25}=\frac{69}{5}=13.8$ Years