00:01
We are told that among young american adults, 17 % are smartphone dependent.
00:08
So that's probability 0 .17 for any randomly selected young american adult.
00:13
And we sample 20 young americans.
00:18
We were asked for the probability that at most 8 are smartphone dependent.
00:22
So the random variable here is the number out of 20 who are smartphone dependent.
00:28
Each of the 20 sampled people are bernoulli trials because there are two of outcomes of interest, either a smartphone dependent or not.
00:37
If we can assume that their outcomes are independent, then the number of successes in a fixed number of independent brunuli trials is a binomial random variable.
00:49
So we can say x is a binomial with parameters n equals 20 trials, p equals 0 .17 probability of success on each trial.
00:58
So we want the probability that at most 8 are smartphone dependent.
01:02
So that's the probability that x is less than are equal to 8.
01:08
This can be solved using software such as excel...