Find the probability that 4 students chosen at random are all born on a wednesday. a) 1/28 b) 1/2401 c) 4/2401 d) 1/254

An automated water dispenser fills packets with one liter of water on average, with a standard deviation of 5 milliliter. the manual says that after a year of operation the dispenser should be tested to see if it needs recalibration. a year later a number of filled packets are set aside and measured separately. it is found that the average packet now contains about 0.995 liters. does the dispenser need calibration? explain your answer.