According to the national center for health statistics in vital statistics of US there is roughly an 80 % chance that a person of age 20 years will be alive at the age of 65. supposed that 3 people of age 20 are selected at random .find the probability that exactly 2 of them will be alive at age 65. supposed that 13 people of age 20 are selected at random find the probability that exactly 9 of them are still alive at age 65