A data set has a range of 25. If every value in the data set is multiplied by 3, what is the range of the new data set?

The range is the largest value minus the smallest value. If every value is multiplied by 3, both the maximum and the minimum are multiplied by 3, so their difference is also multiplied by 3: $3 \times 25 = 75$. Example: values 10 and 35 have range 25; tripled they become 30 and 105, with range 75. A common wrong answer is 28, which comes from adding 3, as would happen if 3 were added to each value (adding a constant leaves the range unchanged, at 25). Multiplication scales the spread, while addition shifts it.