To find out how far up the bar for red will go in Maxwell's bar graph, we need to determine the percentage of red marbles in relation to the total number of marbles.
Maxwell has 7 red marbles out of a total of 28 marbles. We can calculate the percentage as follows:
\[ \text{Percentage of red marbles} = \left( \frac{\text{Number of red marbles}}{\text{Total number of marbles}} \right) \times 100 \]
Substituting in the values:
\[ \text{Percentage of red marbles} = \left( \frac{7}{28} \right) \times 100 = 0.25 \times 100 = 25% \]
Therefore, the bar for red will go up to 25% on Maxwell's bar graph.
The correct response is:
up to 25%