Question:
The average (arithmetic mean) of five numbers is 14. If four of the numbers are 10, 12, 18, and 20, what is the fifth number?
The average (arithmetic mean) of five numbers is 14. If four of the numbers are 10, 12, 18, and 20, what is the fifth number?
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To find a missing number when the average is known, multiply the average by the total count to get the total sum, then subtract the known numbers' sum.
Updated On: Oct 4, 2025
- 8
- 10
- 12
- 14
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The Correct Option is B
Solution and Explanation
Let the fifth number be \( x \). The total sum of the five numbers is:
\[
5 \times 14 = 70.
\]
The sum of the given four numbers is:
\[
10 + 12 + 18 + 20 = 60.
\]
Therefore, the value of the fifth number is:
\[
x = 70 - 60 = 10.
\]
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