6. at a construction site, cement, sand, and gravel are used to make concrete. the ratio of cement to sand to gravel is 1 to 2.4 to 3.6. if a 150-lb bag of sand is used, how much cement and gravel must be used?

A)-in the process of engineering design, explain the contribution of material selection. b)- explain the procedure of synthesis as is employed in engineering design. c)- is there any relationship between ergonomics and engineering design? explain. d)- safety consideration in engineering design includes human, product and the enviroment . explain how safety will be incorporated into the design?