Acertain measurement is performed 50 times. the arithmetic mean reading is 7.163 ft., and the standard deviation is 0.01 ft. how many readings fall within, a) ±0.005 ft b) ±0.02ft (c) ±0.05ft. c) 0.001 ft. of the mean value?

Air (c-1.006 kj/kg.k, r-0.287 kj/kg.k) enters a nozzle steadily at 280 kpa and 77°c with a velocity of 50 m/s and exits at 85 kpa and 320 m/s. the heat losses from the nozzle to the surrounding medium at 20°c are estimated to be 3.2 kj/kg. determine (a) the exit temperature and (b) the total entropy change for this process. solve this problem using constant specific heats.