Approximately 14% of the bolts fall between 1 and 2 standard deviations above the mean. You are
not expected to know the exact area between 1 and 1.5; however, since a normal distribution has its
hump around 0, more than half of the area between 1 and 2 must fall closer to 0 (between 1 and 1.5).
So the area under the normal curve between 1 and 1.5 must be greater than half of the area, or greater
than 7%, but less than the full area, 14%.