Input: Indigenous peoples of the Americas
Contact with European diseases such as smallpox and measles killed between 50 and 67 per cent of the Aboriginal population of North America in the first hundred years after the arrival of Europeans. Some 90 per cent of the native population near Massachusetts Bay Colony died of smallpox in an epidemic in 16171619. In 1633, in Plymouth, the Native Americans there were exposed to smallpox because of contact with Europeans. As it had done elsewhere, the virus wiped out entire population groups of Native Americans. It reached Lake Ontario in 1636, and the lands of the Iroquois by 1679. During the 1770s, smallpox killed at least 30% of the West Coast Native Americans. The 177582 North American smallpox epidemic and 1837 Great Plains smallpox epidemic brought devastation and drastic population depletion among the Plains Indians. In 1832, the federal government of the United States established a smallpox vaccination program for Native Americans (The Indian Vaccination Act of 1832).

Who were the Native Americans exposed to smallpox because of?
Output: Europeans

Input: Article: Harper Lee has remained famously detached from interpreting the novel since the mid-1960s. However, she gave some insight into her themes when, in a rare letter to the editor, she wrote in response to the passionate reaction her book caused: "Surely it is plain to the simplest intelligence that To Kill a Mockingbird spells out in words of seldom more than two syllables a code of honor and conduct, Christian in its ethic, that is the heritage of all Southerners."

Now answer this question: According to Lee, her book simply expressed a Christian code of honor and conduct inherit to whom?

Output: all Southerners

Article: Tracks of the Northern Pacific Railroad (NPR) reached Montana from the west in 1881 and from the east in 1882. However, the railroad played a major role in sparking tensions with Native American tribes in the 1870s. Jay Cooke, the NPR president launched major surveys into the Yellowstone valley in 1871, 1872 and 1873 which were challenged forcefully by the Sioux under chief Sitting Bull. These clashes, in part, contributed to the Panic of 1873 which delayed construction of the railroad into Montana. Surveys in 1874, 1875 and 1876 helped spark the Great Sioux War of 1876. The transcontinental NPR was completed on September 8, 1883, at Gold Creek.

Question: What years were the railroad challenged by Chief Sitting Bull?
Ans: 1871, 1872 and 1873

Here is a question about this article: The chemistry of zinc is dominated by the +2 oxidation state. When compounds in this oxidation state are formed the outer shell s electrons are lost, which yields a bare zinc ion with the electronic configuration [Ar]3d10. In aqueous solution an octahedral complex, [Zn(H
2O)6]2+ is the predominant species. The volatilization of zinc in combination with zinc chloride at temperatures above 285 C indicates the formation of Zn
2Cl
2, a zinc compound with a +1 oxidation state. No compounds of zinc in oxidation states other than +1 or +2 are known. Calculations indicate that a zinc compound with the oxidation state of +4 is unlikely to exist.
What is the answer to this question: What oxidation state dominates zinc?
****
So... +2

The problem: Answer a question about this article:
The ECB's first supplementary longer-term refinancing operation (LTRO) with a six-month maturity was announced March 2008. Previously the longest tender offered was three months. It announced two 3-month and one 6-month full allotment of Long Term Refinancing Operations (LTROs). The first tender was settled 3 April, and was more than four times oversubscribed. The 25 billion auction drew bids amounting to 103.1 billion, from 177 banks. Another six-month tender was allotted on 9 July, again to the amount of 25 billion. The first 12-month LTRO in June 2009 had close to 1100 bidders.
What is an LTRO?
****
The answer: longer-term refinancing operation

The problem: Answer a question about this article:
Bell is also credited with developing one of the early versions of a metal detector in 1881. The device was quickly put together in an attempt to find the bullet in the body of U.S. President James Garfield. According to some accounts, the metal detector worked flawlessly in tests but did not find the assassin's bullet partly because the metal bed frame on which the President was lying disturbed the instrument, resulting in static. The president's surgeons, who were skeptical of the device, ignored Bell's requests to move the president to a bed not fitted with metal springs. Alternatively, although Bell had detected a slight sound on his first test, the bullet may have been lodged too deeply to be detected by the crude apparatus.
What did Bell think was wrong with the bed, which prevented his machine from finding the bullet?
****
The answer:
metal bed frame