Question

Two points are on a number line at 1 and 5. The original weighted average is 2, with a ratio of 3:1. (1 point) When the ratio changes to 4:1, the new weighted average becomes

Answer 1

Let the weights on 1 and 5 be 4 and 1. Then the weighted average is (4·1 + 1·5)/(4+1) = (4+5)/5 = 9/5 = 1.8.