I believe you have it right. Odds that all changes are improvements in 10 changes is: (.95)^10 Odds that at least one change is not improvement is: 1-(.95)^10

I believe you have it right. Odds that all changes are improvements in 10 changes is: (.95)^10 Odds that at least one change is not improvement is: 1-(.95)^10 = 0.40 One could probably make an argument that not all trials are independent, but not sure what else down-voters saw.