00:01
For this exercise, we are told that 25 % of children miss exactly one day of school each year.
00:10
So if x is a number of days of school missed, the probability for missing one is 0 .25.
00:18
We're told that 15 % missed two days, and 28 % miss at least three days of school per year.
00:29
And so for part a, we were asked for the probability that a randomly selected student doesn't miss any days of school during the year.
00:38
Now one thing we know about any probability distribution is that the sum of its probabilities adds up to 1.
00:51
That's for all possible outcomes.
00:55
So what that means is this role must add up to 1.
01:17
And then if we solve for the probability that x equals 0, we get 0 .32.
01:28
So we can say that the probability of a randomly selected student, not missing any school days due to sickness, year is .32.
01:45
Next for part b we are asked for the probability that the randomly selected student misses no more than one day.
01:53
That is the probability that x is at most 1.
01:59
That is simply the sum of the probability that x is 0 plus the probability that x is 1.
02:21
And that comes out to 0 .57.
02:26
And we are also asked for the probability that the student misses at least one day.
02:47
So these three terms are represented by these three probabilities.
02:53
First one is the probability that x is equal to 1.
02:55
The second is that it is equal to 2.
02:58
And the third is the probability that x is at least 3.
03:12
And this comes out to probability of 0 .68th.
03:17
So that is the probability of a randomly selected student missing at least one day of school due to sickness this year.
03:27
And then we're asked to consider a parent who has two kids at the school.
03:31
What is the probability that neither kid will miss any school? so we have already found the probability for one kid not missing any school...