A month ago John O’Hagan increased expenditure on banner ads to $6,000 per month, and no...

A month ago John O’Hagan increased expenditure on banner ads to $6,000 per month, and noticed that the traffic at OHaganBooks.com has not increased to the level predicted by the linear model in Exercise 26. Fitting a quadratic function to the available data gives the model

where h is the daily traffic (hits) at the Web site, and c is the monthly advertising expenditure.

a. According to this model, what is the current traffic at the site?

b. Does this model give a reasonable prediction of traffic at expenditures larger than $8,500 per month? Why?