Correct Answer - Option 1 : 59.5 kg

**Given:**

Average weight of 20 students = 60 kg

**Concept used:**

Average is the central value of a given set of values.

**Formula Used:**

Average = (Sum of Values/Number of Values)

**Calculation:**

As, the sum of weight of 20 students = 60 kg

Sum of the weight of 20 students = 20 × 60 = 1200 kg

As, it was later discovered that one weight was misread as 80 kg instead of 70 kg.

⇒ Difference = 80 - 70 = 10 kg

Actual sum of the weight of 20 students = 1200 - 10 = 1190 kg

Actual average = 1190/20 = 59.5 kg

**∴ The correct average is 59.5 kg.**