Explanation
Correct answer: B.
Choice B is correct. The median of a set of numbers is the middle number when the values in the set are ordered from least to greatest. There are fish, so in an ordered list of the weights, the th value would be the median weight. The fish in tank A weigh the least, and these weights would be the first values on the ordered list. The fish in tank B have the next set of higher weights, and so would be the th through st weights in the ordered list, which includes the median weight as the th value. The fish in tank B weigh at least ounces but no more than ounces; of the given choices, only ounces falls within this range of values.
Desmos solution:
Note: The median is the 17th value. Tank A fills positions 1–10, Tank B fills positions 11–21, so the median must be between 5 and 13. Only 8 fits.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. It's given that tank A has ten fish weighing less than ounces. Since there are more than ten fish in tanks B and C combined, the median weight cannot be less than ounces.
Choice C
Choice C is incorrect. It's given that tank C has twelve fish weighing more than ounces. There are more than twelve fish in tanks A and B combined, so the median weight can't be more than ounces.
Choice D
Choice D is incorrect. It's given that tank C has twelve fish weighing more than ounces. There are more than twelve fish in tanks A and B combined, so the median weight can't be more than ounces.