For the answer to the question above, you will find probabilities for continuous r.v.'s like P(a < X < b) you just find the area under the density curve (what you have called the distribution). In this case, that's finding the area of a rectangle which means that if you can calculate sq ft for carpeting, you can do this problem.
For example,
e) (0.76 - 0.23)*1 = 0.53
For this problem the answer is the area above the interval:
eg. the probability of a) is 0.4 x height or 0.4 x 1 = 0.4.
I hope I helped you with my answer