Ten consecutive strength tests are available for a new concrete mixture with fc= 4000 psi: 4830, 4980, 3840, 4370, 4410, 4890, 4450, 3970, 4780, and 4040psi a. Do the strength results represent concrete of satisfactory quality? Explain
b. If f'cr, has been selected based on 30 consecutive test results from an earlier project with a sample standard deviation Ss, of 570 psi, must the mixture proportions be adjusted? Explain.

Two flowing streams of argon gas are adiabatically mixed to form a single flow/stream. one stream is 1.5 kg/s at 400 kpa and 200 c while the second stream is 2kg/s at 500 kpa and 100 ? . it is stated that the exit state of the mixed single flow of argon gas is 150 c and 300 kpa. assuming there is no work output or input during the mixing process, does this process violate either the first or the second law or both? explain and state all your assumptions.