Answer Happy

An experiment was performed to compare the fracture toughness of high purity 18- Ni maraging steel with commercial purity steel of the same type. The experiment was full randomised and gave the following results for the hardness of the steels (coded units). High Purity Steel Ordinary Steel N 26 28 mean 65.6 59.8 S 1.2 1.1 Because the high-purity steel is more expensive, its use for a certain application can be justified only if its fracture toughness exceeds that of commercial purity steel by more than 5 units. Do the results of the study suggest that this is the case? (Hint: use a one-tailed testing procedure).