45. The population of the United States is shown below for the given years.

Year

1800

1850

1900

1950

1980

2000

Population (in millions)

5

23

76

151

227

281

(a)

Use appropriate scale to plot these six ordered pairs.

(b)

Calculate the average rate of change in the population from 1900 to 1980.

(c)

Present your answer in part(b) in one sentence.

46. Graph 2x y = 1.

(a) Find the x-intercept and the y-intercept.

(b) Use (a) to graph the equation.

47. Graph the solution set of the inequality 2x y 2.

(a) First graph the equation 2x – y = 2.

(b) Use one point to check the inequality. (Specify the point you used.)

48. Solve by substitution method. (Show your work step by

step.)

49. Solve by addition method. (Show your work step by

step.)

50. With the wind, a plane flies 420 miles in 3 hours. Against the wind, the

plane requires 4 hours to fly the same distance. Find the rate of the plane

in calm air and the rate of the wind.

Rate

Time

Distance

With the wind

3 hrs

420 miles

Against the wind

4 hrs

420 miles

Let c = the rate of the plane in calm air.

Let w = the rate of the wind.