The mean of five numbers is . Four of the numbers are . What is the fifth number?
Answer and explanation
Correct answer: D. 18
- Step 1: Calculate the required sum of all five numbers: .
- Step 2: Sum the four given numbers: .
- Step 3: Subtract the known sum from the total sum: .
Answer
18.
Why not the others: - 23 is one of the four given numbers in the set. - 25 is the mean of the numbers. - 13 adds rather than subtracts the constant term in the final step in .
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