7 pupils of average age 12 years leave a class of 25 pupils of average age 14 years . If 6 new pupils of average age 11 years join the class, what is the average age of the pupils in the class?

Answer 1

Let's first find the total age of the 7 pupils who left:

7 x 12 = 84

And the total age of the 25 pupils who remained:

25 x 14 = 350

So the total age of all the pupils before the new ones arrived was:

84 + 350 = 434

Now let's add the age of the 6 new pupils:

6 x 11 = 66

The total age of all the pupils after the new ones arrived is:

434 + 66 = 500

And finally, the average age of all the pupils in the class is:

500 / 31 = 16.13 (rounded to two decimal places)

Therefore, the average age of the pupils in the class is 16.13 years.