The article “Ultimate Load Capacities of Expansion Anchor Bolts” (J. of Energy Engr., 1993: 139–158) gave the following summary data on shear strength (kip) for a sample of 3/8-in. anchor bolts: n = 78, x̅ = 4.25, s = 1.30. Calculate a lower confidence bound using a confidence level of 90% for true average shear strength.