) Consider the instrumental variable regression model Yi = β0 + β1Xi + β2Wi + ui , (1) where Xi is correlated with ui , Wi is uncorrelated with ui , and Zi is an instrument. (a) (8 points) What are the two conditions for Zi to be a valid instrumental variable?

a net is a diagram that shows a “flattened” view of a solid. in a net, each face and base is shown with all of its dimensions. a net can also serve as a pattern to build a three-dimensional solid.

a pyramid is a three-dimensional object with a base that is a polygon and triangular faces that meet at one vertex.

" the net of a triangular pyramid consists of four triangles. the base here we are given of the pyramid is a equilateral   triangle, and the lateral faces are also triangles "

coins of silver or gold

step-by-step explanation:

the first option is the answer.