Mean
Median
Range
Standard deviation
Explanation
Correct answer: B.
Choice B is correct. The median weight is found by ordering the horses' weights from least to greatest and then determining the middle value from this list of weights. Decreasing the value for the horse with the lowest weight doesn't affect the median since it's still the lowest value.
Desmos solution:
Note: Compare the median values from lines 3 and 8 to see which statistic stays the same.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. The mean is calculated by finding the sum of all the weights of the horses and then dividing by the number of horses. Decreasing one of the weights would decrease the sum and therefore decrease the mean.
Choice C
Choice C is incorrect. Range is the difference between the highest and lowest weights, so decreasing the lowest weight would increase the range.
Choice D
Choice D is incorrect. Standard deviation is calculated based on the mean weight of the horses. Decreasing one of the weights decreases the mean and therefore would affect the standard deviation.