Final answer:
The probability that if three residents are chosen at random, they all refuse to pump their own gas is 0.328509.
Step-by-step explanation:
To find the probability that all three residents chosen at random refuse to pump their own gas, we need to multiply the probability of one resident refusing with the probability of another resident refusing and so on. Since 69% of residents refuse to pump their own gas, the probability of one resident refusing is 0.69. So, the probability that all three residents refuse is 0.69 * 0.69 * 0.69 = 0.328509.