Correct Answer - Option 1 : 60

**Given**

Marks scored in first semester = 25

**Formula used**

Average = Sum of all observation/Number of observation

**Calculation**

Marks in first semester = 25

Marks in second semester = 25 + 35

Marks in third semester = 25 + 35 + 35

Average of 3 semesters = [25 + (25 + 35) + (25 + 35 + 35)]/3

⇒ (25 + 60 + 95)/3

⇒ 180/3

⇒ 60

**∴ Average marks in three semesters is 60**