Hello can you please assist me with this practice question I am doing.

Econ 3210 Midterm, Page 2 of 12 October, 2015 1. A professor decides to run an experiment to determine how time pressure during an exam affects test scores. To do this, the professor assigns each student in a class of 400 students a test time. The assignment of the test time is random. Denote the test time by the variable X, which can take on values of 90 (short exam) or 120 (long exam). That is, X, is given by: Xi = 0 if test time is short; 120 if test time is long. Exam grades are out of a 100, and denoted by Yr, where 0