Correct Answer - Option 2 : 24.3 yrs

**Given:**

Total student = 12

Average age = 24 years

The age of the student who left the class = 22 and 23 years

**Formula used:**

Average = The sum of all student age/Total number of student

**Calculation:**

Average = The sum of all student age/Total number of student

⇒ 24 = The sum of all student age/12

⇒ The sum of all student age = 288

According to the question,

The sum of the ages of student who left the class = 22 + 23

⇒ The sum of the ages of student who left the class = 45

Now,

The age of remaining students = 288 - 45

⇒ The age of remaining students = 243

The number of remaining student = 10

New average,

Average = 243/10

⇒ Average = 24.3

**∴ The new average of the class is 24.3 years.**