On a Saturday night, 20%of all drivers in U.S.A. are under the influence of alcohol. The probability that a drive under the influence of alcohol will have an accident is 0.001. The probability that a sober drive will have an accident is 0.0001. if a car on a Saturday night smashed into a tree, the probability that the driver was under the influence of alcohol is `3//7` b. `4//7` c. `5//7` d. `6//7`