The arithmetic mean of the observations 25, 63, 86, 90, 13, 72, 74, 16 and 47…
2025
The arithmetic mean of the observations 25, 63, 86, 90, 13, 72, 74, 16 and 47 is:
- A.
63
- B.
46
- C.
54
- D.
56
Attempted by 28 students.
Show answer & explanation
Correct answer: C
Concept: The arithmetic mean (average) of a set of n observations is the sum of all the observations divided by the number of observations.
Mean = (Sum of observations) / n
List the nine observations: 25, 63, 86, 90, 13, 72, 74, 16, 47.
Add all the observations to get the total: 25 + 63 + 86 + 90 + 13 + 72 + 74 + 16 + 47 = 486.
Count the number of observations: n = 9.
Divide the total by the count: 486 ÷ 9 = 54.
Cross-check: grouping the values differently — (25+90) + (63+13) + (86+16) + (72+74) + 47 = 115 + 76 + 102 + 146 + 47 = 486 — gives the same total, confirming the mean is 486 ÷ 9 = 54.
Hence, the arithmetic mean of the given observations is 54.