Final answer:
The function y = 4 * (0.8)^t is an exponential decay function, representing the decrease of a quantity over time, with y being the value at time t. To find y at any given t, substitute t into the equation and calculate the result.
Step-by-step explanation:
The given function y = 4 * (0.8)^t is an exponential decay function, where y represents the value of the function at time t, the number 4 is the initial value of the function when t = 0, and 0.8 is the decay factor relevant for each time unit. This type of function is often used in contexts such as radioactive decay, depreciation of value over time, or population decrease in a closed environment, where some quantity decreases by a consistent percentage over equal time intervals.
To solve for y at a given time t, simply substitute the value of t into the function and evaluate the exponential expression. It is important to use a calculator or software tool to evaluate the exponential term accurately when t is not a round number.