Asampling of 409 motor shafts from a very large production batch shows a sample standard deviation in diameter of 0.021 mm with a sample mean of 9.251 mm estimate the mean diameter of the entire batch at a %95 level of confidences?

An air-conditioning system consists of a heating section and an evaporative cooler. air enters the heating section at 10°c and 70 percent relative humidity at a rate of 30m^3/min, and it leaves the evaporative cooler at 20°c and 60 percent relatively humidity. if the air conditioning system operates at a total pressure of 98 kpa, determine (a) the temperature and relative humidity of the air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate of water added to air in the evaporative cooler