Question

Difficulty: MediumOrder and Ranking

In a consolidated merit list of 90 applicants for a university fellowship, Marcus is ranked 25th25^{\text{th}} from the top, while Elena is ranked 44th44^{\text{th}} from the bottom. If David is positioned exactly in the middle of Marcus and Elena in this merit list, what is David's rank from the bottom?

  1. A
    54th54^{\text{th}}
  2. B
    45th45^{\text{th}}
  3. 55th55^{\text{th}}Answer
  4. D
    36th36^{\text{th}}

Answer

David's rank from the bottom is the 55th55^{\text{th}} position.
To find David's position, we first standardise the reference points. Elena's 44th44^{\text{th}} position from the bottom corresponds to the 47th47^{\text{th}} position from the top (calculated as 9044+190 - 44 + 1). The exact midpoint between the 25th25^{\text{th}} and 47th47^{\text{th}} ranks is the 36th36^{\text{th}} rank from the top (calculated as the average: (25+47)/2=36(25 + 47) / 2 = 36). Finally, converting David's 36th36^{\text{th}} top rank to a bottom rank yields 9036+1=55th90 - 36 + 1 = 55^{\text{th}}.

Step-by-Step Solution

1
Convert Elena's bottom rank to a top rank to establish a common directional reference.
Elena's rank from the top is 9044+1=47th90 - 44 + 1 = 47^{\text{th}}.
To calculate the number of people strictly between Marcus and Elena, both ranks must be measured from the same end (the top).
2
Calculate the number of applicants positioned strictly between Marcus and Elena.
There are 47251=2147 - 25 - 1 = 21 applicants between them.
Subtracting the top ranks and deducting 1 excludes both Marcus and Elena from the middle count.
3
Determine David's exact relative position starting from Marcus.
David is the 11th11^{\text{th}} person after Marcus.
The exact midpoint of 21 people is (21+1)/2=11(21 + 1) / 2 = 11 positions away from the starting person.
4
Calculate David's overall absolute rank from the top.
David's top rank is 25+11=36th25 + 11 = 36^{\text{th}}.
Adding David's relative interval to Marcus's top rank yields David's absolute top rank.
5
Convert David's top rank back to a bottom rank to answer the final question.
David's rank from the bottom is 9036+1=55th90 - 36 + 1 = 55^{\text{th}}.
Applying the standard linear ranking formula: Total=Top Rank+Bottom Rank1\text{Total} = \text{Top Rank} + \text{Bottom Rank} - 1.

Key Concept

Positional overlap calculation and dual-rank directional conversion
Rate this question