Use the following data to answer questions #21 through #24: For an air conditioning system, 1,000 cfm of outdoor air at 90F DB & 78F WB is mixed with 2,500 cfm of return air at 72F and 50% RH (Hint: use psychrometric chart or calculate) 21. Determine the mixed air temperature (DB condition) of the 3,500 cfm total mixed air: a. 72F b. 73F C. 77F d. 90F 22. Determine the wet bulb temperature of the mixed air: a. 72F b. 66F C. 68F d. 82F 23. Determine the dew point temperature of the mixed air: a. 66F b. 72F c. 55F d. 60F 24. Determine the humidity ratio (Specific humidity) of the return air: a. 59 Grains/Lb dry air b. 65 Grains/Lb dry air c. 50 Grains/Lb dry air d. 32 Grains/Lb dry air Page 4 of 6