Correct Answer - Option 1 : 68 kg

**GIVEN:**

Total student = 100

Average of whole class = 60

Girls = 40% of Total student

⇒ Average of girls = 48

**ASSUMPTION:**

Let the average weight of boys = Y

**FORMULA USED:**

⇒ Average = Sum of observations/number of observations ----(1)

**CALCULATION:**

⇒ Sum of observations = 6000

⇒ Girls = 40

⇒ Boys = 60

According to the question

⇒ 40 x 48 + 60 x Y = 6000

⇒ Y = 68

⇒ Average of boys = 68