Input: Translation
Comparison of a back-translation with the original text is sometimes used as a check on the accuracy of the original translation, much as the accuracy of a mathematical operation is sometimes checked by reversing the operation. But the results of such reverse-translation operations, while useful as approximate checks, are not always precisely reliable. Back-translation must in general be less accurate than back-calculation because linguistic symbols (words) are often ambiguous, whereas mathematical symbols are intentionally unequivocal.

What symbol set has a defining property of ambiguity?
Output: linguistic

Input: FC Barcelona
In 1978, Josep Lluís Núñez became the first elected president of FC Barcelona, and, since then, the members of Barcelona have elected the club president. The process of electing a president of FC Barcelona was closely tied to Spain's transition to democracy in 1974 and the end of Franco's dictatorship. The new president's main objective was to develop Barcelona into a world-class club by giving it stability both on and off the pitch. His presidency was to last for 22 years, and it deeply affected the image of Barcelona, as Núñez held to a strict policy regarding wages and discipline, letting go of such players as Maradona, Romário and Ronaldo rather than meeting their demands.

Who was the first elected president of the Barcelona club?
Output: Josep Lluís Núñez

Input: Light-emitting diode
The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994 and was based on InGaN. In parallel, Isamu Akasaki and Hiroshi Amano in Nagoya were working on developing the important GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN. Nakamura, Akasaki and Amano were awarded the 2014 Nobel prize in physics for their work. In 1995, Alberto Barbieri at the Cardiff University Laboratory (GB) investigated the efficiency and reliability of high-brightness LEDs and demonstrated a "transparent contact" LED using indium tin oxide (ITO) on (AlGaInP/GaAs).

Who demonstrated the first blue LED?
Output: Shuji Nakamura

Input: Northwestern University
Northwestern has several housing options, including both traditional residence halls and residential colleges which gather together students who have a particular intellectual interest in common. Among the residential colleges are the Residential College of Cultural and Community Studies (CCS), Ayers College of Commerce and Industry, Jones Residential College (Arts), and Slivka Residential College (Science and Engineering). Dorms include 1835 Hinman, Bobb-McCulloch, Foster-Walker complex (commonly referred to as Plex), and several more. In Winter 2013, 39% of undergraduates were affiliated with a fraternity or sorority. Northwestern recognizes 21 fraternities and 18 sororities.

What percentage of undergraduates were affiliated with a fraternity or sorority in Winter 2013?
Output:
39%