Blue Bus

P is negligently run off the road into a parked car by a blue bus. P is prepared to prove that D operates four-fifths of all the blue buses that use the route. What effect, if any, should such proof be given?⁽¹⁾

^{1. This problem is based on Tribe, Trial by Mathematics: Precision and Ritual in the Legal Process, 84 Harv. L. Rev. 1329, 1341 (1971).}