Question 9
In the table below, each letter represents the number of students in that category. Which of the following must be equal to z?
STUDENTS IN ADVANCED BIOLOGY CLASS
Category | Juniors | Seniors | Total
--- | --- | --- | ---
Boys | k | n | m
Girls | r | s | t
Total | w | x | z
A. k + s
B. m + x
C. r + s
D. r + s + t
E. k + n + r + s
**Editorial note for this self-study exercise:** The row and column categories partition the students: every student is counted in exactly one of the four inner cells. Enter one option letter A–E. Letter case and outside whitespace are ignored.
STUDENTS IN ADVANCED BIOLOGY CLASS
Category | Juniors | Seniors | Total
--- | --- | --- | ---
Boys | k | n | m
Girls | r | s | t
Total | w | x | z
A. k + s
B. m + x
C. r + s
D. r + s + t
E. k + n + r + s
**Editorial note for this self-study exercise:** The row and column categories partition the students: every student is counted in exactly one of the four inner cells. Enter one option letter A–E. Letter case and outside whitespace are ignored.