Algebra-1

Question Analysis
This question involves a two-way frequency table with variables "grade" (6th/7th) and "transportation to school" (walk/bus).
The main focus is on finding a missing joint frequency using the row marginal frequency for 7th grade.

Key Concept Explanation
Row Marginal Frequency: The total number of observations in a row, calculated as the sum of all joint frequencies within that row.
For 7th grade, this means: Row total (7th grade) = joint frequency (walk) + joint frequency (take the bus).

Step-by-Step Solution
Locate the row for "7th Grade," which has a row total of 90.The known joint frequency for 7th graders who walk to school is 36.
Let the missing joint frequency (7th graders who take the bus) be x.Using the row total relationship: 36 + x = 90.
Solve for x:

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