A professor decides to run an experiment to measure the effect of time pressure on final exam scores. He gives each of the 400 students in his course the same finalâ exam, but some students have 90 minutes to complete the exam while others have 120 minutes. Each student is randomly assigned one of the examination times based on the flip of a coin. Let Yi denote the number of points scored on the exam by the ith studentâ (0<= Yi<= â100), let Xi denote the amount of time that the student has to complete the exam â( âXi = 90 orâ 120), and consider the regression model â, Which of the following are true about the un-observable â? â(Check all that applyâ)

a. Different students will have different values of because they have unobserved individual specific traits that affect exam performance.
b. represents factors other than time that influence theâ student's performance on the exam.
c. All students will necessarily have the same value of because they are part of the same population.
d. will be zero for all students because time spent studying is likely the only factor that affects exam performance

The chromosome manufacturing company produces two products, x and y. the company president, jean mutation, is concerned about the fierce competition in the market for product x. she notes that competitors are selling x for a price well below chromosome's price of $13.50. at the same time, she notes that competitors are pricing product y almost twice as high as chromosome's price of $12.50.ms. mutation has obtained the following data for a recent time period: product x product y number of units 11,000 3,000 direct materials cost per unit $3.23 $3.09 direct labor cost per unit $2.22 $2.10 direct labor hours 10,000 3,500 machine hours 2,100 1,800 inspection hours 80 100 purchase orders 10 30ms. mutation has learned that overhead costs are assigned to products on the basis of direct labor hours. the overhead costs for this time period consisted of the following items: overhead cost item amount inspection costs $16,200 purchasing costs 8,000 machine costs 49,000 total $73,200using direct labor hours to allocate overhead costs determine the gross margin per unit for product x. choose the best answer from the list below. a. $1.93b. $3.12c. $7.38d. $2.43e. $1.73using activity-based costing for overhead allocation, determine the gross margin per unit for product y. choose best answer from list below. a. $10.07b. ($2.27)c. ($5.23)d. ($7.02)e. $7.02