1. A company had its sales persons undergo training, hoping to improve their sales. Past sales data indicate that the average sale was P4,000 per transaction on a normally distributed population....

Extracted text: 1. A company had its sales persons undergo training, hoping to improve their sales. Past sales data indicate that the average sale was P4,000 per transaction on a normally distributed population. After training, sales data, taken from a random sample of 25 salesmen/salesladies, indicates an average sale of P4,500 with a standard deviation of P150. (a) Write the null hypothesis. (b) Write the alternative hypothesis. (c) Formulate and calculate the test-statistic. Is it a one-tail or two- tailed test? Did the training work at 95% confidence level? (d) Determine the confidence interval.