Stats problem with probablity

Question

According to a recent poll of 1,108 U.S. adults, 50% believe in reincarnation. Suppose that 8 adults are randomly selected from among the 1,108 who were surveyed. Answer the following questions. Round your answers to three decimal places; add trailing zeros as needed.

The probability that at least 7 of the 8 adults believe in reincarnation is  .

The probability that all of the selected adults believe in reincarnation is 

Answer 1

This involves Bernoulli or binomial probability (same thing). The probability that exactly r "successes" in n trials occurs is (nCr)*p^r*q^(n-r), where p is the probability of a success, and q is the probability of a failure. If we decide that a success is an adult believing in reincarnation, then p = .50, and failure is not believing, q = 1-p = .50. For exactly 7 successes in 8 tries nCr = 8C7 = 8 (your calculator can do this calculation if it has a MATH key and you go to PROB) *,5^7*,5 = .5^8 = =8*.0039=0.03129.But your problem says AT LEAST 7, so you need to do the calculation with 8 successes in 8 tries, = (8C8)*(.5)^8*(.5)^0 = .0039, so .03129 + .0039 = .0519

The other problem is similar.