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.

On a average work day more than work place firs are reorted

A2-m rigid tank initially contains saturated water vapor at 100 kpa. the tank is connected to a supply line through a valve. steam is flowing in the supply line at 600 kpa and 300 c. the valve is opened, and steam is allowed to enter the tank until the pressure in the tank reaches the line pressure, at which point the valve is closed. a thermometer placed in the tank indicates that the temperature at the final state is 200°c. determine (a) the mass of steam that has entered the tank (b) the amount of heat transfer.

Aplate of dimensions 3 m x 3 m is placed 0.37 mm apart from a fixed plate. the plate requires a force of 2n to move at speed of 45 cm/s. evaluate the viscosity of the fluid in between the plates