A survey is planned to compare salaries of plant managers in two regions. The plan is to take a sample of 400 plant managers from each region and ask their annual salaries. Assume that previous sample statistics suggest that of = 62 = $5000. Are the sample sizes sufficient to produce a 95% confidence interval on 1 - H2 having a width of only $1200? Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. The sample sizes sufficient because the samples would need to be at least people each, which is the planned sample sizes of 400. (Round up to the nearest whole number as needed.) A random sample of 15 chocolate energy bars of a certain brand has, on average, 240 calories per bar, with a standard deviation of 25 calories. Assume that the distribution of the calorie content is approximately normal. Construct a 90% confidence interval for o. Click here to view page 1 of the table of critical values of the chi-squared distribution. Click here to view page 2 of the table of critical values of the chi-squared distribution. The confidence interval is