Correct Answer - Option 3 : 20 kg

**Given:**

The cost price of tea is Rs. 40, Rs. 50, Rs. 80 and Rs. 70 and the mean price is Rs. 60.

Possible value of cost price which can mean price of Rs. 60 are (40, 80) and (50, 70)

**Calculation:**

Using rule of alligation,

Ratio of tea of cost price of Rs. 40 and Rs. 80 are mixed = (80 – 60) : (60 – 40)

= 1 : 1

Ratio of tea of cost price of Rs. 50 and Rs. 70 are mixed = (70 - 60) : (60 – 50)

= 1 : 1

Ratio of tea of cost price Rs. 40, Rs. 50, Rs.80 and Rs.70 are mixed = 1 : 1 : 1 : 1

Required quantity of tea of Rs. 80 = ¼ × 80 = 20 kg