Question

north middle school survey results
grade museum zoo total
grade 6 106 185 291
grade 7 145 166 311
grade 8 182 162 344
total 433 513 946
central middle school survey results
grade museum zoo total
grade 6 155 172 327
grade 7 179 185 364
grade 8 162 135 297
total 496 492 988
which comparison about the number of students in each category is correct?
{grade 6 students at north who chose zoo} < {grade 6 students at central who chose museum}
{grade 7 students at north who chose museum} < {grade 7 students at central who chose zoo}
{grade 8 students at north who chose zoo} > {grade 8 students at central who chose museum}
{all students at north who chose museum} > {all students at central who chose museum}

Explanation:

Step1: Find Grade 6 students at North who chose zoo

From North Middle - School table, for Grade 6, number of students who chose zoo is not given (assuming no Grade 6 in North Middle - School survey). But we can still check other options.

Step2: Find Grade 7 students at North who chose museum

From North Middle - School table, Grade 7 students who chose museum is 145.

Step3: Find Grade 7 students at Central who chose zoo

From Central Middle - School table, Grade 7 students who chose zoo is 185.
Since 145 < 185, the comparison {Grade 7 students at North who chose museum} < {Grade 7 students at Central who chose zoo} is correct.
We can also check the other remaining options:

Step4: Find Grade 8 students at North who chose zoo

From North Middle - School table, Grade 8 students who chose zoo is 162.

Step5: Find Grade 8 students at Central who chose museum

From Central Middle - School table, Grade 8 students who chose museum is 162. So {Grade 8 students at North who chose zoo}={Grade 8 students at Central who chose museum}, and the third option is incorrect.

Step6: Find all students at North who chose museum

From North Middle - School table, total students who chose museum is 433.

Step7: Find all students at Central who chose museum

From Central Middle - School table, total students who chose museum is 496. So {All students at North who chose museum} < {All students at Central who chose museum}, and the fourth option is incorrect.

Answer:

{Grade 7 students at North who chose museum} < {Grade 7 students at Central who chose zoo}