5.102 The supply office for a large construction firm has three welding units of Brand A in stock. If a welding unit is requested, the probability is 0.7 that the request will be for this particular brand.

On a typical day, five requests for welding units come to the office. Find the probability that all three Brand A units will be in use on that day.

gyp(y) = 1 P[Y(t ) = n] = aN - 1 k - 1 b e-lkt(1 - e-lt)n-k