Probability sum...

Asked by syscon | 29th Jan, 2010, 08:17: PM

Expert Answer:

If you are asking about the question 15.1 from Optional Exercises, but note that you mentioned a week, while the exercise mentions Tue to Sat, only 5 days.

Each customer can go on any of the 7 days of the week. If they go on different days that is 6 possibilities or days are available for second customer,

Hence probability that they'll go on different days = 6/7

Probability that they go on same day = 1- probability that they go on different days. 1 - 6/7 = 1/7

Since first customer can decide any of 7 days, he has 7 choices, similarly second also has 7 choices.

Hence the total no of way is 7x7 = 49.

For the consecutive days, first customer can select any of 7 days and for second customer then the choice is only one, the consecutive day.

So there are 7 different ways, but the so called second customer can always be exchanged and called first customer, hence 7 more.

Total number of ways for consecutive visits, = 14.

Probability for consecutive day visits = 14/49

= 2/7






Answered by  | 29th Jan, 2010, 10:55: PM

Queries asked on Sunday & after 7pm from Monday to Saturday will be answered after 12pm the next working day.