The average marks obtained by three students is 15. If two students obtained 12 and 18 marks respectively, find the marks obtained by the third student.

15 marks

Step-by-step explanation:

If the average mark obtained by 3 students is 15, then the total marks are

⇒ 3 x 15 = 45

Let x be the marks obtained by the third student.

If two students obtained 12 and 18 marks, then

⇒ 12 + 18 + x = 45

⇒ 30 + x = 45

⇒ x = 45 - 30

⇒ x = 15

Solution:

We can clearly say that "mean" has been used.

In this case, we are given three numbers, 12, x, and 18.

The marks obtained by the third student is 15 marks.