00:01
For this question, this is a probability question, and the number of modems here, which is 220.
00:10
So let me just say the sample space here, which is the total number of modems, which is equal to 2020.
00:18
And the 33 of the modems are defective.
00:21
So the number of defective here, which is 3 .3.
00:27
And what about the not de facto one? so the not de facto one, which is 20, 20 and minus 33, which is equal to 1 ,987.
00:40
So we're going to select 55 modems.
00:43
So we need to get that all of them are not defective.
00:47
So first of all, let's find the probability of not defective.
00:51
And i'm going to define this probability as the p, which is equal to 1987, and divided by the total number of modems here.
01:01
This is 987 divided by 2020, which is equal to 0 .98 and 37.
01:09
So we're going to select 55, so the n here, which is 55 here.
01:15
So i'm going to use the binomial distribution...