Indicate which variable you think should be the predictor (x) and which variable should be the response (y). Explain your choices.

a. Weights of nuggets of gold (in ounces) and their market value over the last few days are provided, and you wish to use this to estimate the value of a gold bracelet that weighs 4 ounces.

b. You have data collected on the amount of time since chlorine was added to the public swimming pool and the concentration of chlorine still in the pool. (Chlorine evaporates over time.) Chlorine was added to the pool at 8 a.m., and you wish to know what the concentration is now, at 3 p.m.

c. You have data on the circumference of oak trees (measured 12 inches from the ground) and their age (in years). An oak tree in the park has a circumference of 36 inches, and you wish to know approximately how old it is.