Polyester resins reinforced with fiberglass are used tofabricate wall panels of restaurants. It is theorized that addingcement kiln dust​ (CKD) to the polyester composite will increasewall panel hardness. In a​ study, hardness​ (joules [J] persquared​ centimeters) was determined for three polyester compositemixtures that used a​ 40% CKD weight ratio. The hardness valueswere reported as 83, 82​, and 77 J/cm2. Research hasshown that the mean hardness value of polyester composite mixturesthat use a​ 20% CKD weight ratio is μ = 76 J/cm2. Inyour​ opinion, does using a​ 40% CKD weight ratio increase the meanhardness value of polyester composite​mixtures? Support youranswers statistically.
