a television commercial claims that 1 out of 4 of todays mar

a television commercial claims that 1 out of 4 of today\'s marriages began as online relationships. assuming that this is true, calculate the following 8 randomly selected todays marriages. The probability that at least 7 began online? The probability that two or three began online.

Solution

1 out of 4 means = 0.25 probability of online relationship

sample of 8

probability of atleast 7 online relationship = 8C7*(0.25)^7*(0.75) + 8C8*(0.25)^8*(0.75)^0 = 0.0003+0.00001 = 0.00031

PROBABILITY 2 OR 3 BEGAN ONLINE = 8C2*(0.25)^2*(0.75)^6 + 8C3*(0.25)^3*(0.75)^5 = 0.311+-.207 = 0.518