Final answer:
The correct term for a function that shows a steady level of cost for a range of output and then jumps to a higher level is a step-cost function. This typically represents situations where additional fixed costs are incurred after a certain production level is surpassed. In regression analysis, the significance of a correlation is determined via statistical testing.
Step-by-step explanation:
The correct answer is d. step-cost function. A step-cost function shows a steady level of cost for an output range and then jumps up to a higher level of cost, where it remains steady for another range of activity. This pattern resembles a staircase, hence the term 'step' cost. In practical terms, this might represent a scenario where once a certain level of production is reached, additional resources are required, leading to an increased fixed cost. For example, a manufacturing company might operate with one set of machinery up to a certain point, but after surpassing that production level, a second set of machinery (and the associated fixed costs) becomes necessary to continue operations efficiently.
An equation typically used to summarize the relationship between two variables is "ŷ = a + bx", where 'a' is the intercept, 'b' is the slope of the line, 'n' represents the number of data points, and 'ŷ' is the predicted value of the dependent variable for a given value of the independent variable. The correlation between two variables can be assessed to determine if there is a significant relationship between them, which is often done via hypothesis testing, looking at the correlation coefficient, or examining the p-value associated with the correlation.