A standard normal table can be used to estimate what part of a normal distribution will fall within a certain range, given the number of standard deviations (or Z-Score) from the mean. 56 minutes is 11 minutes from 45, and the standard deviation is 8, so the Z-Score is 11/8 = 1.375. The lookup table gives 8.5% complementary probability (greater than the given number of standard deviations) for 1.37 and 8.4% for 1.38. Checking a graph, the part of the curve above 1.375 standard deviations should be somewhere between 5 and 10%, so this seems reasonable.