From the chart, we can see that $\displaystyle 21\%$ of the school population is freshmen. Thus, we will need to find $\displaystyle 21\%$ of $\displaystyle 1200$.

$\displaystyle \text{Number of Freshmen}=(0.21)(1200)=252$

The sector labeled "Juniors" takes up $\displaystyle 23\%$ of the circle. Thus, its central angle must be $\displaystyle 23\%$ of $\displaystyle 360$, the number of total angles in a circle.

$\displaystyle \text{Central Angle}=(0.23)(360)=82.8$

The central angle must be $\displaystyle 82.8$ degrees.

The juniors and seniors make up $\displaystyle 54\%$ of the school's population. Thus, we can find the number of juniors and seniors.

$\displaystyle \text{Number of Juniors and Seniors}=(0.54)(1200)=648$

The freshmen and sophomores make up $\displaystyle 46\%$ of the school's population. Thus, we can find the number of freshmen and sophomores.

$\displaystyle \text{Number of Freshmen and Sophomores}=(0.46)(1200)=552$

Subtract these two numbers to find how many more juniors and seniors there are than freshmen and sophomores.

$\displaystyle 648-552=96$

There are $\displaystyle 96$ more juniors and seniors than there are freshmen and sophomores.

The question "Of the five schools, which school's median score improved the most from last year?" requires knowledge of last year's median math scores, which are not given by the graph. The other three questions only require knowledge of this year's scores, which are given.

The median score at Wallace was 69, so Juanita scored above the median. By definition, she outscored at least half the seniors, which means that she must have outscored at least $\displaystyle 188 \div 2 = 94$ of them. The correct response must be greater than or equal to 94, and the only choice that fits that criterion is 105.

Julio scored the highest of the three with 71, so we are looking for a high school whose median score was above 71. Of the four choices, only Garner fits this criterion.

Of the five schools, only Burr had median scores below 70 in both 2012 and 2013. The correct choice is "one".

The number of students who scored in the 601-700 range is 16; in the 701-800 range, 10. Add them to get 26 students total.

40 students achieved a score of 501-600; 16 achieved a score of 601-700; 10 achieved a score of 701-800. Add these:

$\displaystyle 40 + 16 + 10 = 66$

The number of students who took the test is the sum of the students who finished in the six ranges:

$\displaystyle 6 + 18 + 30 + 40 + 16 + 10 = 120$

The question is now to find out what percent 66 is of 120, which can be calculated as follows:

$\displaystyle \frac{66}{120} \100 \% = 55 \%$

By making a 673, Clarissa finished in the second-highest range shown (601-700). She was outscored by at least 10 students (the ones in the 701-800 range), but by at most 25 students (the 10 in the 701-800 range plus the other 15 in the 601-700 range). She finished between 11th and 26th, inclusive, so the only plausible choice is 14th.