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In a published civil services merit list, Rohan is ranked 14th14^{\text{th}} from the top, while Seema is ranked 33rd33^{\text{rd}} from the bottom. After a re-evaluation of marks, Rohan and Seema interchange their positions, resulting in Rohan becoming 48th48^{\text{th}} from the top. A third candidate, Amit, holds a rank exactly halfway between Rohan's new position and Seema's new position. If 66 candidates ranked above Amit withdraw their candidature and 44 new candidates are placed below Amit in the updated list, what is Amit's final rank from the bottom of the modified merit list?

Cevap: 54

Cevap

Amit's final rank from the bottom of the modified merit list is 54.
Seema's dual information (48th48^{\text{th}} from top and 33rd33^{\text{rd}} from bottom) gives an initial total of 80 candidates. Amit's midpoint position between 14th14^{\text{th}} and 48th48^{\text{th}} is 31st31^{\text{st}} from top, placing 49 candidates below him. Accounting for 6 withdrawals above and 4 additions below leaves 53 candidates below Amit, establishing his final rank as 54th54^{\text{th}} from the bottom.

Adım Adım Çözüm

1
Find total candidates in the original merit list using the interchange data.
Total candidates N = 80
When Rohan and Seema interchange positions, Rohan occupies Seema's original spot (48th48^{\text{th}} from top). Since Seema was 33rd33^{\text{rd}} from bottom, N=48+331=80N = 48 + 33 - 1 = 80.
2
Calculate Amit's initial rank from the top.
Amit's initial top rank = 31st
Amit is positioned halfway between Seema's new position (14th14^{\text{th}} from top) and Rohan's new position (48th48^{\text{th}} from top), so rank = (14+48)/2=31st(14 + 48) / 2 = 31^{\text{st}}.
3
Find initial counts of candidates ranked above and below Amit.
30 candidates above, 49 candidates below
With a top rank of 31st31^{\text{st}} out of 80, there are 311=3031 - 1 = 30 candidates above Amit and 8031=4980 - 31 = 49 candidates below Amit.
4
Adjust counts based on candidate withdrawals and additions.
24 candidates above, 53 candidates below
Subtract 6 from candidates above (306=2430 - 6 = 24) and add 4 to candidates below (49+4=5349 + 4 = 53).
5
Calculate Amit's revised rank from the bottom.
54th from the bottom
The rank from the bottom equals (candidates below + 1), which gives 53+1=5453 + 1 = 54.

Anahtar Kavram

Dual Rank Position Interchange, Midpoint Computation, and Dynamic List Adjustment
Tahmini Süre:2m 30s
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