When a new product is advertised, more and more people try it. However, the rate at which new people try it slows as time goes on.

Consider the following six graphs.

1.a graph in the first quadrant of a decreasing, concave down function with positive y-intercept.2.a graph in the first quadrant of a decreasing, concave up function with positive y-intercept.3.a graph in the first quadrant of an increasing, concave down function starting at the origin.
4.a graph in the first quadrant of a linear, decreasing function with a positive y-intercept.5.a graph in the first quadrant of a linear, increasing function passing through the origin.6.a graph in the first quadrant of an increasing, concave up function with positive y-intercept.

Which of these graphs could be a reasonable sketch of the graph of the total number of people who have tried such a product against time?

What can you say about the concavity of the graph? It is .

You can earn partial credit on this problem.