Question

The average of 17 results is 60. If the average of the first 9 results is 57 and that of the last 9 results is 61, Then the 9th result is.
1. 42
2. 45
3. 39
4. 41

Answer 1

Correct Answer - Option 1 : 42

GIVEN:

Average of 17 results = 60

Average of first 9 results = 57

Average of last 9 results = 61

FORMULA USED:
Average = Sum of observations/Total number of observations

CALCULATION:
Sum of 17 results = 17 × 60 = 1020

Sum of first 9 results = 9 × 57 = 513

Sum of last 9 results = 9 × 61 = 549

9th result = (513 + 549) – 1020

⇒ 1062 – 1020

⇒ 42

∴ The 9th result is 42.