Final answer:
The wall thickness of extra-strong 8-inch pipes depends on various factors and cannot be determined without referencing specific standards. Calculations of gauge pressure in a tapered pipe require fluid dynamics principles, including Bernoulli's equation.
Step-by-step explanation:
The question about the wall thickness of extra-strong pipes is specifically related to engineering standards for pipe construction. Unfortunately, without a reference to a particular standard or code such as the ASME (American Society of Mechanical Engineers) B36.10, which provides specifications for pipe wall thickness, it is not possible to give a specific wall thickness for an 8-inch pipe or larger. Wall thickness can vary depending on the material, the pressure it needs to withstand, and other factors.
Similarly, to calculate the gauge pressure required in a tapered pipe scenario, where one end has a diameter twice as large as the other, and water needs to exit with a specific speed, we would apply principles of fluid dynamics. For this question, the specific calculations would involve Bernoulli's equation and the continuity equation, considering factors such as the elevation of the pipe, the speed of water at the smaller end, and the dimensions of the pipe.