Saguaro cacti are large cacti indigenous to the southwestern United States and Mexico. Assume that the number of saguaro cacti in a region follows a Poisson distribution with a mean of 280 per square kilometer. Determine the following:

(a) Mean number of cacti per 10,000 square meters.

(b) Probability of no cacti in 10,000 square meters.

(c) Area of a region such that the probability of at least two cacti in the region is 0.9.