7. In a bay the time between high tide and low tide is approximately 6 hours. The first low tide is at 7 a. m. followed by a hide tide at 1 p. m. The depth of the water in the bay at low tide is 5 fathoms which rises to 9 fathoms at high tide. a) Sketch a graph of the depth of the water in the bay over time. Start your graph at 7 a. m. and graph at least on complete cycle. b) Write a function equation for your curve. Let t represent the number of hours after 7 a. m. c) How deep will the water be at 11 a. m? ​

Data from 2005 for various age groups show that for each $100 increase in the median weekly income for whites, the median weekly income of blacks increases by $105. also, for workers of ages 25 to 54 the median weekly income for whites was $676 and for blacks was $527. (a) let w represent the median weekly income for whites and b the median weekly income for blacks, and write the equation of the line that gives b as a linear function of w. b = (b) when the median weekly income for whites is $760, what does the equation in (a) predict for the median weekly income for blacks?