solve problems using given graphs or equations of exponential functions arising from a variety of real-world applications (e.g., radioactive decay, population growth, height of a bouncing ball, compound interest) by interpreting the graphs or by substituting values for the exponent into the equations Sample problem: The temperature of a cooling liquid over time can be modelled by the exponential function , where is the temperature, in degrees Celsius, and is the elapsed time, in minutes. Graph the function and determine how long it takes for the temperature to reach 28°C.