Problem: Washington University has a large number of student-run musical groups on campus, including 12 official a cappella groups. The Pikers, an all-male group, is the oldest such group on campus. The Greenleafs, an all-female group is the oldest (and only) female group on campus. The Mosaic Whispers, founded in 1991, is the oldest co-ed group on campus. They have produced 9 albums and have appeared on a number of compilation albums, including Ben Folds' Ben Folds Presents: University A Cappella! The Amateurs, who also appeared on this album, is another co-ed a cappella group on campus, founded in 1991. They have recorded seven albums and toured extensively. After Dark is a co-ed a cappella group founded in 2001. It has released three albums and has won several Contemporary A Capella Recording (CARA) awards. In 2008 the group performed on MSNBC during coverage of the vice presidential debate with specially written songs about Joe Biden and Sarah Palin. The Ghost Lights, founded in 2010, is the campus's newest and only Broadway, Movies, and Television soundtrack group. They have performed multiple philanthropic concerts in the greater St. Louis area and were honored in November 2010 with the opportunity to perform for Nobel Laureate Douglass North at his birthday celebration.
How many a cappella groups does Washington University have?
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Answer: 12

Problem: Although the format was capable of offering higher-quality video and audio than its consumer rivals, the VHS and Betamax videocassette systems, LaserDisc never managed to gain widespread use in North America, largely due to high costs for the players and video titles themselves and the inability to record TV programming. It also remained a largely obscure format in Europe and Australia. By contrast, the format was much more popular in Japan and in the more affluent regions of Southeast Asia, such as Hong Kong, Singapore, and Malaysia, being the prevalent rental video medium in Hong Kong during the 1990s. Its superior video and audio quality did make it a somewhat popular choice among videophiles and film enthusiasts during its lifespan.
Why didn't LaserDisk gain popularity in North America?
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Answer: high costs for the players and video titles themselves and the inability to record TV programming

Problem: However many early history books like the Islamic Conquest of Syria Fatuhusham by al-Imam al-Waqidi state that after the conversion to Islam Muawiyah's father Abu Sufyan ibn Harb and his brothers Yazid ibn Abi Sufyan were appointed as commanders in the Muslim armies by Muhammad. Muawiyah, Abu Sufyan ibn Harb, Yazid ibn Abi Sufyan and Hind bint Utbah fought in the Battle of Yarmouk. The defeat of the Byzantine Emperor Heraclius at the Battle of Yarmouk opened the way for the Muslim expansion into Jerusalem and Syria.
Who was the Byzantine leader at the Battle of Yarmouk?
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Answer:
Heraclius