In a learning curve application, 658.5 work hours are required for the third production unit and 615.7 work hours are required for the fourth production unit. Determine the value of n (and therefore s) in the equation Z U=K(u^n ), where u=the output unit number; Z_=the number of input resource units to produce output unit u; K=the number of input resource units to produce the first output unit; s=the learning curve slope parameter expressed as a decimal (s=0.9 for a 90% learning curve); n=log⁡s/log⁡2 =the learning curve exponent.