A survey of 52 U.S. supermarkets yielded the following relative frequency table, where X is the number of checkout lanes at a randomly chosen supermarket. 1 2 3 4 5 8 9 10 6 7 0.30 0.15 0.09 P(X = x) 0.01 0.03 0.03 0.09 0.10 0.15 0.05 (a) Compute = E(X). HINT [See Example 3.] E(X). Interpret the result. There were at least this many checkout lanes in each supermarket that was surveyed. There were, on average, this many checkout lanes in a supermarket that was surveyed. This was the most frequently observed number of checkout lanes in surveyed supermarkets. There were at most this many checkout lanes in each supermarket that was surveyed. (b) Find P(X ). P(x ) =