GP11: Two electric car engine/battery systems A and B were compared. The amount of miles driven on a single charge was measured. Fifty experiments were conducted using battery type A and seventyve were conducted on B. Find the probability that the average mileage of system A was at least 4 miles lower than the average mileage of system B. Assume that the manufacturers claim population means & standard deviations for the systems are 36 & 6 (for A} and 42 & 8 (for B)