Part 1 Cape Breton University is accessed from Grand Lake Road, which is a busy highway that carries 40 000 cars per day, with a posted speed limit of 80 km/h. Below are vehicle speeds recorded in km/h by the Royal Canadian Mounted Police in front of CBU over a 10 minute period - the police want to know if there is a problem with speeding at this location. 85 70 80 85 90 80 95 100 75 80 Does this data represent a population or a sample? Answer Sample How many observations were reported? Answer 10 Calculate the following: Mean Answer 84 Median Answer 82.5 Mode Answer 80 Range Answer 30 Standard Deviation Answer 8.88 Skewness (sk) Answer 0.46 How symmetrically distributed is this data? Answer Approximately Symmetrical Part 2 In order for the police to decide whether or not to be concerned about this data, they want to develop a 90% confidence interval. Should a t or z distribution be used? Answer t-distribution Calculate the following: t or z value Answer 1.833 Margin of Error Answer 7.905 Lower limit Answer 76.09 Upper limit Answer 91.90 Based on this confidence interval, is it reasonable to say that the average driver: i) exceeds the speed limit at this location? Answer Yes ii) travels at over 90 km/h at this location? Answer Yes iii) might travel at 85 km/h at this location? Answer Inconclusive Part 3 What does FPC stand for? Answer Finite Population Correction What expression below is used to calculate an FPC? Answer A Calculate the FPC for this data Answer What rule of thumb is used to determine whether an FPC should be used? A < B A: Answer n/N B: Answer 0.05 Calculate the rule of thumb for this data Answer Should an FPC be used to correct the standard error for this data? Answer Can't tell Part 4 Consider the above to be a pilot study. If the police now want to conduct a larger study that is more precise (i.e. a higher level of confidence with a smaller margin of error), how large of a sample size do they need? Calculate the following to complete the table: E 1 km/h Level of Confidence 95% z Answer Standard Deviation Answer What sample size n is required? Answer