The Graph Below Shows the Total Sales (In Thousands of Dollars)

Multiple Choice

The graph below shows the total sales (in thousands of dollars) in a supermarket during a typical 24-hour period. (i) Estimate the rate of sales during the period from 6 A.M. to 12 noon.
(ii) Which 6-hour interval sees the highest rate of sales and what is this rate?

A) (i) $167/hr
(ii) 6pm to 12 noon
B) (i) $1167/hr
(ii) noon to 6pm
C) (i) $667/hr
(ii) 12 noon to 6 pm $1167/hr.
D) none of these