Let x1 and x2 be independent chi-square random variables with r1 and r2 degrees of freedom, respectively. let y1 = (x1/r1)/(x2/r2) and y2 = x2. (a) find the joint pdf of y1 and y2. (b) determine the marginal pdf of y1 and show that y1 has an f distribution. (this is another, but equivalent, way of finding the pdf of f.)

Aprism and two nets are shown below: image of a right triangular prism and 2 nets. the triangle bases have base 4, height 3, and diagonal side 5. the length of the prism from the bases is 9.4. net a has 3 rectangles in a row. the middle one has sides ac and cd. this middle one has triangle abc on top and identical triangle below. net b is the same except that the triangle base abc is on top of the last rectangle which has sides ac and cd. units are in inches. part a: which is the correct net for the prism? explain your answer. (2 points) part b: write the measurements of sides ab, bc, and cd of the correct net. (4 points) part c: what is the surface area of the prism? show your work. (4 points)