Final answer:
The function y = (2/5)^x represents exponential decay, not growth. The exponential decay is indicated by the base of the exponent, (2/5), being less than 1, which leads to a decrease in y as x increases.
Step-by-step explanation:
The function y = (2/5)^x represents an exponential decay because the base of the exponent, (2/5), is between 0 and 1. In an exponential growth, the base would be greater than 1, which makes the value of y increase as x increases. However, in this case, as x increases, the value of y decreases, which is characteristic of exponential decay.
Considering an exponential graph, the x-axis would represent the independent variable x, while the y-axis would represent the dependent variable y. The decay rate is determined by the base (2/5). To create a visual demonstration relevant to the probability example provided, we would need additional context such as the relationship between the amount of money in a student's pocket and the decaying function. However, in general, shading the area under the curve to the left of x = 0.40 would illustrate P(x < 0.40), assuming x represents the amount of money in dollars.