Astatistics practitioner in a large university is investigating the factors that affect salary of professors. he wondered if evaluations by students are related to salaries. to this end, he collected 100 observations on:

Ahelical coil spring has a mean diameter of 50 mm, a wire diameter of 5.5 mm and is wound with a pitch of 10 mm. the spring steel has an ultimate strength of 1250 mpa. find the force needed to compress the spring solid and the wire stress in this condition. state whether the spring will return to its initial length.