This is another important chapter to master. Especially try to understand the conditions and situations that apply to the various distributions. Especially helpful is the on-line text Hyperstat . Data acquired from counting is usually discrete.
Measured data is usually continuous.
Therefore, the integral over the range of x must equal 1. Solve for k that makes this condition hold. Keep in mind that x ranges from 0 to infinity for this distribution when setting up your integrals. See section 4-8, page 195. Now you do not have to integrate to find the probability because the integral has been converted into a generalized function of x.