The slant shear test is widely accepted for evaluating the bond of resinous repair materials to concrete; it utilizes cylinder specimens made of two identical halves bonded at 30 degrees. A recent study on different bonding techniques reported that for 12 specimens prepared using wire-brushing, the sample mean shear strength were 19.2 N/mm² with a standard deviation of 1.58. For specimens that were prepared with a hand chisel, reported a mean shear strength of 23.13 N/mm² with a standard deviation of 4.01. Does the true shear strength appear to be different for the two methods of surface preparation? State and test the relevant hypothesis using a significant level of alpha = .05. What are the state Ho and Ha, Critical T or Z value, Calculated T or Z, as well as the decision?