Seven number set: The sum of seven numbers is 235. The average of the first three is 23 and that of the last three is 42. Find the fourth number.
Aptitude
Average
Difficulty: Easy
Choose an option
Answer
Correct Answer: 40
Explanation
Introduction / Context:This is a partition of totals problem where we remove the known blocks to get the central term.Given Data / Assumptions:
- Total of seven = 235
- First three average = 23
- Last three average = 42
Concept / Approach:Compute sums of the first and last triplets, subtract from the grand total to obtain the middle (fourth) element.Step-by-Step Solution:
Sum first three = 3 * 23 = 69Sum last three = 3 * 42 = 126Fourth number = 235 - (69 + 126) = 40Verification / Alternative check:Recompose totals to confirm the grand total remains 235.Why Other Options Are Wrong:
- 126 and 195 are component sums, not the standalone fourth value.
- 69 is the first triplet sum, not the fourth element.
Common Pitfalls:Mixing sums with single values or forgetting there are seven numbers in total.Final Answer:
40