Sorry, misunderstood question, answer beneath me much better.
<h3>
Explanation:</h3>
In the graph x-coordinate represents the number of wind chimes sold and y-coordinate represents the profit Madison earned. If a point is below the x-axis, means it has negative y-coordinate than it represents loss. Points above x-axis should have x-coordinate more than 6 as stated in the question that she started earning profit after selling her first 6 wind chimes. All the points having x-coordinate less than 6 should lie on or below the x-axis.
By the above statement point B is completely wrong. Point C and Point A are also wrong as they both x-coordinate more than 6 but still they are below x-axis.
Point D is the makes most sense here as it has x-coordinate more than 6 and it is above x-axis. This means that when Madison sold 7 wind chimes she was in a profit of $3.75.
The answer should be 0.5x^4+12.5
In this problem, volume is computed:
volume = ∫(flow rate)·dt
.. = ∫[0, t] (3/10)*sin(2πt/7)·dt
= (3 / 10)*(7 /(2 π))*(-cos (2 π t/7)+1)
= (-21 / (20 π))*(cos (2 π t /7) - 1)
Volume is equal to 21 sin^2 (pit/7) / 10pi is the inhaled air in the lungs at time t