Question: Marketing and Consumer Behavior After analyzing a database of over 2 million telephone calls, Vonage reported that the mean length of all international calls was 295 seconds. Following an extensive advertising campaign, the company expected the length of international calls to increase. A few months after the ads first appeared, a random sample of 48 calls was obtained. The sample mean was x¯ = 306.3 seconds. Assume that the population standard deviation is 52 seconds. Is there any evidence to suggest the advertising campaign has been successful? Use a = 0.01.