Content Prioritization for Standards-based Education/Show me how the range of high, medium, and low priority is established.

Begin by subtracting the lowest possible score from the highest, then adding one. The one is added to compensate for inclusiveness. The result is the number of possible scores.

150 - 30 = 120 + 1 = 121 possible scores.

Next, divide the number of possible scores by three. This will tell you how many possible answers are within each group.

121 ÷ 3 = 40⅓

Since 30 is the lowest possible score, we know that any score that falls within 40⅓ points of it also falls in the lowest third of possible answers. Obviously there will be no fractional scores, so we can find the boundary between low and medium by adding 40⅓ to one less than the lowest possible answer (again to compensate for inclusion) and rounding.

(30 - 1) + 40⅓ = 69⅓ rounded to 69

The lowest scoring range is from 30 to 69. This means the boundary between high and low priority is between 69 and 70 in this case. To establish the upper boundary of the medium range, we add 40⅓ to the original, un-rounded boundary, then round the sum.

69⅓ + 40⅓ = 109⅔ rounded to 110

The medium scoring range is 69 to 110. The remaining possible scores make up the highest scoring third. This means the range of the highest scoring third is 111 to 150