Question

for a certain section of a pine forest, the number of diseased trees per acre, Y, has a Poisson distribution with mean A=10. The diseased trees are sprayed with an insecticide at a cost of $3 per tree, plus a fixed overhead cost for equipment rental of $50. Letting C denote the total spraying cost for a randomly selected acre,within what interval would you expect C to lie with probability of at least 0.75?.