A consulting firm has devised a short course that is supposed to improve the writing

skills of the employees of large companies. The Personnel Office of a corporation is

considering buying the short course, but first they do a preliminary study. Two samples

of employees are selected. The writing skills of the employees in the first sample are

measured in a scale of $1$ to $100,$ where high scores indicate good writing skills. The other

employees in the second sample take the short course and their writing skills are

measured in the same scale, after completion of the course. Here are the sample results: