Problem: With 39,000 acres (158 km2), the Tallgrass Prairie Preserve in north-central Oklahoma is the largest protected area of tallgrass prairie in the world and is part of an ecosystem that encompasses only 10 percent of its former land area, once covering 14 states. In addition, the Black Kettle National Grassland covers 31,300 acres (127 km2) of prairie in southwestern Oklahoma. The Wichita Mountains Wildlife Refuge is the oldest and largest of nine national wildlife refuges in the state and was founded in 1901, encompassing 59,020 acres (238.8 km2).
The Tallgrass Prairie Preserve is the largest protected tallgrass prairie in what area?
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Answer: the world

Problem: Roughly one-third of the world's population has been infected with M. tuberculosis, with new infections occurring in about 1% of the population each year. However, most infections with M. tuberculosis do not cause TB disease, and 9095% of infections remain asymptomatic. In 2012, an estimated 8.6 million chronic cases were active. In 2010, 8.8 million new cases of TB were diagnosed, and 1.201.45 million deaths occurred, most of these occurring in developing countries. Of these 1.45 million deaths, about 0.35 million occur in those also infected with HIV.
About how many people died in 2010 carrying both HIV and TB?
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Answer: 0.35 million

Problem: Modern navies that operate such aircraft carriers treat them as the capital ship of the fleet, a role previously held by the battleship. This change took place during World War II in response to air power becoming a significant factor in warfare, driven by the superior range, flexibility and effectiveness of carrier-launched aircraft. Following the war, carrier operations continued to increase in size and importance. Supercarriers, displacing 75,000 tonnes or greater, have become the pinnacle of carrier development. Some are powered by nuclear reactors and form the core of a fleet designed to operate far from home. Amphibious assault ships, such as USS Tarawa and HMS Ocean, serve the purpose of carrying and landing Marines, and operate a large contingent of helicopters for that purpose. Also known as "commando carriers" or "helicopter carriers", many have the capability to operate VSTOL aircraft.
What do Amphibious assalut ships need a large contingent of for carrying Marines?
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Answer:
helicopters