A private agency claims that the special crash program it offers significantly increases the writing speed of the office secretaries. The following table gives the writing speeds of seven secretaries before and after they attended this course.

Before 75 72 85 90 65 70 77

After 80 75 93 97 70 65 83

Using the Wilcoxon signed-rank test at 5% significance level, can you conclude that attending this course increases the writing speed of secretaries? Mention all formulae and necessary steps. Assume that the population of paired differences has a normal distribution.