Thread: need help on probability

My Solution::
b i) no answer
b ii) no answer
b iii) no answer

Originally Posted by littlemissy

From the long experience, a staff in casino found that the duration a visitor would spend in the casino per visit is normally distributed with the mean 90 minutes and standard deviation 20mins

1)If one visitor was selected randomly, find the probability that he would spend
a) more than 100minutes
b) between 80 minutes and 130 minutes
...

You should have a table of the standard normal distribution.

Let , where is the time a punter spends in the casino in minutes, then has a standard normal distribution.

a) That corresponds to

If you have a table of the cumulative standard normal you can look up on that table to tell you but .

b) That corresponds to or

If you have a table of the cumulative standard normal you can look up on that table to tell you and to tell you , then

RonL

Quention 2 is hard for me....sorry cant help