Which of the following building components keep opposite walls from spreading apart

Two technicians are discussing how to test a car's exhaust by holding a small piece of paper within an inch of the tailpipe mouth. technician a says that if the paper is vibrating due to a "puffing" output from the tailpipe, this signals a smoothly running engine. technician b says that if the paper is being drawn toward the tailpipe, this could indicate burned exhaust valves. who is correct? a. technician b b. both technicians a and b c. technician a d. neither technicians a or b

How are students who take the writing portion of accuplacer graded?

Apopulation of bolts has a mean thickness of 20 millimeters, with a population standard deviation of .01 millimeters. give, in millimeters, a minimum and a maximum thickness that includes 68% of the population of bolts.