4. The city historical museum director believes that a tourist's decision to come to the museum depends largely on the tourist's age and the number of days that he or she is visiting the city. She uses data from the city's annual survey of tourists to regress whether the tourist visited the museum on the tourist's age (X₁) and length of stay in days (X₂). She finds that ; s.e._b1 = 0.002; s.e._b2 = 0.025; R² = .40; n = 400.

(a) Interpret the slope of X₁.

(b) Interpret the p-value of the slope of X₁.

(c) Interpret the R-squared.

(d) What is the probability that a 50-year-old tourist who is visiting the city for four days will come to the museum?