3: given that main memory is composed of three page frames for public use and that a program requests pages in the following order: a, b, a, b, f, d, f, c, g, f, g, b, d, e a) using the fifo page removal algorithm, perform a page trace analysis indicating page faults with asterisks (*). then compute the failure and success ratios. b) using the lru page removal algorithm, perform a page trace analysis and compute the failure and success ratios c) what conclusions do you draw from this comparison of fifo and lru performance? would you make general statements from this example? explain why or why not.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?