The average of 29 observations is 40. If the average of the first 15 observations is 38, and that of the last 15 observations is 45, then the 15th observation is:
Show answer & explanation
Correct answer: C
Explanation
The Correct answer is Option 3 i.e.85.
We know that,
Average = Sum of observations/Number of observations
Sum of 29 observations = 29 × 40 = 1160
Sum of first 15 observations = 15 × 38 = 570
Sum of last 15 observations = 15 × 45 = 675
Hence,
15th observation will be = (570 + 675) - 1160
⇒ 1245 - 1160 = 85