As we shall illustrate in Chapter 12, statistical methods associated with linear and nonlinear models are very important. In fact, exponential functions are often used in a wide variety of scientific and engineering problems. Consider a model that is fit to a set of data involving measured values k and k and a certain response Y to the measurements. The model postulated is where denotes the estimated value of Y, k and k are fixed values, and b , b , and b are estimates of constants and hence are random variables. Assume that these random variables are independent and use the approximate formula for the variance of a nonlinear function of more than one variable. Give an expression for . Assume that the means of b , b , and b are known and are β , β , and β , and assume that the variances of b , b , and b are known and are , and .