Question 6.157

59. Abandoning Landlines. The Centers for Disease Control reported in 2014 that 41% of U.S. households use only cell phones (no landline) (Source: http://www.pewresearch.org/fact-tank/2014/07/08/two-of-every-five-u-s-households-have-only-wireless-phones/). Suppose we take a random sample of 12 telephone users.

  1. Find the probability that the sample contains exactly four users who use cell phones only.
  2. Find the probability that the sample contains, at most, four users who use cell phones only.
  3. Find the probability that the sample contains between four and six users inclusive who use cell phones only.

6.2.59

(a) 0.2054 (b) 0.4101 (c) 0.6189