an oil prospector will drill a succession of holes attempting to find a productive well. assume the probability of being successful on any drilling is 0.15, and that outcomes of drillings are independent. what is the expected number of drilling attempts needed in order to find a productive well? what is the probability that the first productive well is found on the third attempt? if the prospector can only afford to drill five holes, what is the probability that the prospector will fail to find a productive well