00:01
In this exercise, we are told that 44 % of recent college graduates plan on pursuing a college degree.
00:08
So that means for any individual recent graduate, this probability is 0 .44.
00:15
And now we consider a random sample of 26 recent college graduates.
00:21
And we're asked for probabilities that certain numbers of these 26 plan to pursue graduate degrees.
00:29
So let's first define a random variable x as the number who plan to pursue a graduate degree out of the sample of 26.
00:37
Now here each of these 26 recent graduates can be viewed as a bernoulli trial.
00:42
There's two outcomes of interest.
00:44
They either plan to pursue a graduate degree or not.
00:47
And since it's a random sample, their outcomes are independent.
00:51
The number of successes in a given number of independent brunuli trials is a binomial random variable.
00:57
So here x is a binomial based on 26 trials and probability of success.
01:02
0 .44.
01:06
The probability mass function for the binomial random variable is given by this formula.
01:23
Now we want the probability that no more than 7, this is for part a, the probability that no more than 7 plan to pursue a graduate degree.
01:33
So this is the probability that x is less than equal to 7.
01:41
Now we could use the probability mass function to solve this by doing this calculation for x equals 0 plus for x equals 0.
01:50
Equals 1 plus for x equals 2 and so on up to 7, which is a bit tedious, so let's use software for this one.
01:57
We can use excel...