A 20 question multiple choice test is given to someone who randonly guesses at all 20 questions. If each question has four answer choices, what us the expected number the person will asnwer correctly?​

The pyraminx is a rubik's cube-type toy in the shape of a tetrahedron. the pyraminx shown below has edges 15\,\text{cm}15cm long and vertical height h=12.2\,\text{cm}h=12.2cm. the triangle drawn with dashed lines is a right triangle. what is the distance rr? round your answer to the nearest tenth.