00:02
The question states that the phone lines to an airline reservation system are occupied 40 % of the time.
00:09
It means that out of 100 calls, 40 calls will be occupied.
00:14
So it is equal to 0 .4.
00:17
In the first part of the problem, we are as to find the probability for exactly 3 calls to be occupied.
00:25
So we need to find the probability of x is equal to 3.
00:30
Here observe that if 40 percentage of calls are occupied it means that there will be 60 percentage of calls that are not been occupied which is equal to 0 .6.
00:43
In the first part of the problem we need to find the probability for exactly three calls to be occupied when 10 calls are placed to the airline.
00:55
Here understand that we have 10 calls and among them we need to choose to be occupied when 10 calls are placed to the airline.
01:00
3 calls exactly 3 calls to be occupied.
01:07
So the required probability consists of the term 10c3 which means we are choosing 3 number of calls among 10 calls and the second thing is we will have the probability 0 .4 3 times and it means that we will have the probability 0 .4 3 times and it means that we will have the probability 0 .6 for remaining 7 times out of 10 times.
01:46
So these three things has to happen.
01:50
In probability whenever we have the term and we need to use product there and if we are having the term or we need to do addition.
02:05
Here we we need to have all these three conditions that is we need to have 0 .5...