6-8   ①  We know that the probability of the particle being found somewhere between 0 and L equals 1 (because it must be somewhere. If there is constant probability density over the range of L, we can therefore say that the probability that the particle will be with in a range of length Δ will be given by:

(Δ / L)  x  1

We have specified that x should be between 0.09L and 0.11L, which is a range of 0.02L.  So the  probability that the particle will be found in this range is given by:

(0.02L / L) x 1 =   0.02


②  We could also have found this using the general method we learned in Chapter 5: