Zagat restaurant guides publish ratings of restaurants for many large cities around the world (see www.zagat.com). The review for each restaurant gives a verbal summary as well as a 0- to 30-point rating of the quality of food, décor, service, and the cost of a dinner with one drink and tip. For 31 French restaurants in Boston in 2014, the food quality ratings had a mean of 24.55 and standard deviation of 2.08 points. The cost of a dinner (in U.S. dollars) had a mean of $50.35 and standard deviation of $14.92. The equation that predicts the cost of a dinner using the rating for the quality of food is ŷ = -70 + 4.9x. The correlation between these two variables is 0.68. (Data available in the Zagat_Boston file.)
a. Predict the cost of a dinner in a restaurant that gets the
(i) Lowest observed food quality rating of 21, 

(ii) Highest observed food quality rating of 28.
b. Interpret the slope in context.
c. Interpret the correlation.
d. Show how the slope can be obtained from the correlation and other information given.