Total marks scored by the whole class = 50 × 60 = 3000 Total mark after excluding highest and lowest = 48 × 59 = 2832 ⇒ Sum of marks of lowest and highest = 3000 – 2832 = 168 Now Let lowest marks be "x" ⇒ Highest mark = x + 120 ⇒ x + x + 120 = 168 ∴ x = 24 Hence the lowest mark is 24