Abrick of 203 × 102 × 57 mm in dimension is being burned in a kiln to 1250°c, and then allowed to cool in a room with ambient air temperature of 30°c and convection heat transfer coefficient of 5 w/m2·k. the brick has properties of rho = 1920 kg/m3, cp = 790 j/kg·k, and k = 0.90 w/m·k. calculate the time required to cool a brick from 1250°c to a temperature difference of 5°c from the ambient air temperature. (round the answer to 2 decimal places.) 7.18 ± 5% hours.