Between 1985 and 2003, data were collected every three years on the amount of plastic produced annually in the United States, in billions of pounds. The graph below shows the data and a line of best fit. The equation of the line of best fit is  , where x  is the number of years since 1985 and y is the amount of plastic produced annually, in billions of pounds.

Which of the following is the best interpretation of the number 3.39 in the context of the problem?

Some building codes require that, for indoor stairways, the tread depth must be at least 9 inches and the riser height must be at least 5 inches. According to the riser-tread formula, which of the following inequalities represents the set of all possible values for the riser height that meets this code requirement?

When designing a stairway, an architect can use the riser-tread formula , where h is the riser height, in inches, and d is the tread depth, in inches. For any given stairway, the riser heights are the same and the tread depths are the same for all steps in that stairway.
The number of steps in a stairway is the number of its risers. For example, there are 5 steps in the stairway in the figure above. The total rise of a stairway is the sum of the riser heights as shown in the figure.

In mathematics, inequalities explain the relationship between two non-equal values. When two values are not equal, we frequently use the "not equal symbol ()" to indicate this. However, many inequalities are used to compare the values and determine whether they are less than or greater.
¶A relationship is considered to be an inequality if it involves two real numbers or algebraic expressions and uses the symbols ">"; "<"; "≥"; "≤. "
¶Since the tread depth, 'd' is at least 9 inches, and the riser height, 'h' is at least 5 inches, it follows that h ≥ 5, and d ≥ 9
respectively. Solving for d in the riser tread formula 2h + d = 25 gives d = 25 - 2h. Thus the first inequality, d ≥ 9, is equivalent to
25-2h ≥ 9.

Solve each inequality and graph the solution :

The function h, defined by , where  a  and  b are constants, models the height, in centimeters, of the sunflower after  t days of growth during a time period in which the growth is approximately linear. What does a represent?

In H. S. Reed and R. H. Holland published a paper on the growth of sunflowers. Included in the paper were the table and graph above, which show the height  h, in centimeters, of a sunflower t days after the sunflower begins to grow.

Which of the following expresses the riser height in terms of the tread depth?

When designing a stairway, an architect can use the riser-tread formula , where h is the riser height, in inches, and d is the tread depth, in inches. For any given stairway, the riser heights are the same and the tread depths are the same for all steps in that stairway.
The number of steps in a stairway is the number of its risers. For example, there are 5 steps in the stairway in the figure above. The total rise of a stairway is the sum of the riser heights as shown in the figure.

Oil and gas production in a certain area dropped
from 4 million barrels in 2000 to 1.9 million barrels
in 2013. Assuming that the oil and gas production
decreased at a constant rate, which of the following
linear functions f best models the production, in
millions of barrels, t years after the year 2000?

Over which of the following time periods is the average growth rate of the sunflower least?

In 1919,H. S. Reed and R. H. Holland published a paper on the growth of sunflowers. Included in the paper were the table and graph above, which show the height h, in centimeters, of a sunflower t days after the sunflower begins to grow.

If , what is the value of ?

Points A and B lie on a circle with radius 1 , and arc  has length . What fraction of the circumference of the circle is the length of arc  ?

An architect wants to use the riser-tread formula to design a stairway with a total rise of 9 feet, a riser height between 7 and 8 inches, and an odd number of steps. With the architect's constraints, which of the following must be the tread depth, in inches, of the stairway? ( 1 foot = 12 inches)

When designing a stairway, an architect can use the riser-tread formula , where h is the riser height, in inches, and d is the tread depth, in inches. For any given stairway, the riser heights are the same and the tread depths are the same for all steps in that stairway.
The number of steps in a stairway is the number of its risers. For example, there are 5 steps in the stairway in the figure above. The total rise of a stairway is the sum of the riser heights as shown in the figure.

A group of 202 people went on an overnight camping trip, taking 60 tents with them. Some of the tents held 2 people each, and the rest held 4 people each. Assuming all the tents were filled to capacity and every person got to sleep in a tent, exactly how many of the tents were 2-person tents?

In the xy -plane, the graph of the equation above is a circle. Point P is on the circle and has coordinates (10, -5). If  is a diameter of the circle, what are the coordinates of point Q?

How many liters of a   saline solution must be added to 3 liters of a  saline solution to obtain a  saline solution?

For the solution (x, y) to the system of equations above, what is the value of  x - y?

What is the sum of the solutions to

In the figure above,  is parallel to . What is the length of  ?