Chapter 20, Problem 52P

An experiment is performed to define the relationship between applied stress and the time to fracture for a type of stainless steel. Eight different values of stress are applied, and the resulting data are

Applied stress x, ${\text{kg/mm}}^2$	5	10	15	20	25	30	35	40
Fracture time y, hr	40	30	25	40	18	20	22	15

Plot these data and then develop a best-fit equation to predict the fracture time for an applied stress of $20{\text{kg/mm}}^2$.