00:01
All right, so in this video, we're going to use normal approximation to estimate the given probability.
00:04
So we're going to be doing p, finding out the probability of x being between 35 and 48.
00:13
So to start, we're just going to identify our parameters.
00:18
So we have n equals 400 and p equals 0 .1.
00:24
In step two, we're going to calculate the mean and standard deviation of the binomial distribution.
00:28
Distribution.
00:29
So mean would be equal to n times p and standard deviation sd would be equal to let me just write this out n times p times 1 minus p and that would just be the square roots of everything under this branch here.
00:53
So i did a calculation beforehand so i got 40 and i got 6 for standard deviation and mean.
01:01
So in step 3, we're going to use the normal approximation to estimate the probability.
01:07
We want to find the probability that x lies in between this range.
01:11
So we're going to convert the binomial distribution to a normal distribution with the same mean and standard deviation.
01:18
We're going to find the z -scores for 35 and 48, and we're going to do that by 35 minus 40.
01:27
So this is our mean, and we're going to divide it by 6, which is our standard deviation, and that gives us approximately negative 0 .8333...