Which sentences use a semicolon correctly?

Henry J. Kaiser, a steelmaker and shipbuilder, originally conceived the idea for the new prototype; however, Howard Hughes and his staff are credited with the actual design and construction of the craft.
By this time, the government had spent an estimated $22 million on the project; Hughes had personally spent $18 million of his own money.
Naismith had to think of something that would encourage everyone to play; and keep him active without being too rough with each other.
Using his vast experience with other sports games, Naismith took bits and pieces of each; in order to meet the parameters he was given.
Always active in athletics and team sports, Naismith created the game of basketball to emphasize athletic skill; while shifting the focus away from the rough play of other popular games such as football and rugby.
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