Find a missing result using averages: The average of five results is 46, and the average of the first four results is 45. What is the fifth result?
Aptitude
Average
Difficulty: Easy
Choose an option
Answer
Correct Answer: 50
Explanation
Introduction / Context:When a total average and a partial average are known, convert both to totals. The difference between these totals gives the missing entry directly.
Given Data / Assumptions:
- Average of five = 46
- Average of first four = 45
Concept / Approach:Compute total of all five and total of first four, then subtract to get the fifth value.
Step-by-Step Solution:
Total of five = 5 * 46 = 230Total of first four = 4 * 45 = 180Fifth result = 230 - 180 = 50Verification / Alternative check:The five values must sum to 230. If the first four sum to 180, the last must be 50. Averages remain consistent.
Why Other Options Are Wrong:
- 51, 49.5, 49, 52: do not satisfy the given averages when recomputed.
Common Pitfalls:Arithmetic slips when multiplying averages or subtracting totals. Keep integers aligned.
Final Answer:50