# Find the 13th result. If

The average of 25 result is 18. The average of first 12 of them is 14 and that of the last 12 is 17. Find the 13th result.

- 71
- 75
- 72
- 78

**Answer: (4) 78
Explanation:-
**The average of 25 results = 18

The sum of 25 results = 18 x 25 = 450

The average of first 12 results = 14

the sum of first 12 results = 14 x 12 = 168

The average of last 12 results = 17

the sum of last 12 results = 17 x 12 = 204

Thus, the 13^{th} number = 450 – (168 + 204)

= 450 – 372

= 78

Hence, the 13^{th} number is 78.