BA 302 - A sample of 25 items yields = 60 grams

. A sample of 25 items yields = 60 grams and s = 3.5 grams. Assuming a normal parent distribution, construct a 99 percent confidence interval for the population mean weight.

3. Of a random sample of 1000 trucks at a bridge, 280 had bad signal lights. Construct a 99 percent confidence interval for the percentage of trucks that had bad signal lights.

4. A cable TV company wants to estimate the percentage of cable boxes in use during an evening hour. An approximation based on previous surveys is 25 percent. The company wants the new estimate to be at the 90 percent confidence level and within 2 percent of the actual proportion. What sample size is needed?

5. Suppose that 50 percent of the voters in a particular region support a candidate. Find the probability that a sample of 1,000 voters would yield a sample proportion in favor of the candidate within 1 percentage points of the actual proportion.

Chapter 10

6. Test H₀:m£ 8 versus H_A:m> 8, givena= 0.01, n = 16, = 8.11 and s = 0.16. Assume the sample is selected from a normally distributed population.

1. Packages of sugar bags for Sweeter Sugar Inc. have a normal distribution with an average weight of 16 ounces and a standard deviation of 0.2 ounces. What is the probability that 25 randomly selected packages will have a weight in excess of 16.060 ounces?