2) The speeds of a random sample of 100 cars are recorded as they pass a highway checkpoint. The results are summarized in the frequency distribution below. Approximate the sample mean. Speed (mph)...

Extracted text: 2) The speeds of a random sample of 100 cars are recorded as they pass a highway checkpoint. The results are summarized in the frequency distribution below. Approximate the sample mean. Speed (mph) Cars 30–39 3 40-49 17 50-59 50 60-69 20 70-79 10 Suppose your hypothesis is H, = 55. Calculate withing a confidence level of 5% if this is reasonable. Secondly give an approximate interval of a 5% confidence level. Note: Recall the following: X is the sample statistic taken from the data on the table. E (xi-E(X)]? s“ or the sample deviation is calculated by п-1 Note that the standard deviation of the statistic Oỹ