The burning rates of two different solid-fuel propellants used in aircrew escape systems are being studied. it is known that both propellants have approximately the same standard deviation of burning rate; that is, σ 1 = σ 2 = 3 cm/s. from a random sample of size n 1 = 20 and n 2 = 20 , we obtain x ¯ 1 = 18.02 cm/s and x ¯ 2 = 24.36 cm/s.

An air compression refrigeration system is to have an air pressure of 100 psia in the brine tank and an allowable air temperature increase of 60°f for standard vapor compression cycle temperatures of 77 f entering the expansion cylinder and 14 f entering the compression cylinder, calculate the coefficient of performance a. 2.5 b 3.3 c. 4.0 d. 5.0