00:01
Hi, i'm david and i'm here here let me bring up your question here here we want to discuss about the normal distribution here we have the x that follows by the normal with the mean and the standard deviation if the x minus the mean of a standard deviation we obtain the standard normal but if we'll take the sum of mean x bar we minus the mean of a standard deviation we need to divide extra squared up n in order to obtain the standard normal here we have the height of the height of the size of the the male x will follow by the normal when the mean equal to the 70 standard division equal to the 2 .8.
00:39
Now in the first question 8, when you find the probability that the height x, it will be between the 67 and the 72.
00:50
Here we need to convert the x into the z.
00:53
To do it, i need to apply this formula here.
00:56
And then it gets equal to 67, we manage the mean.
01:00
Over the 2 .8, 72 minus 70 over the 2 .8.
01:06
And if we compute, we have the z will be 3, the minus 2 .8, equal to the minus 1 .07.
01:16
Here we have the 2 divided by 2 .8 equal to the 0 .7 1 ,4.
01:24
Now, if we use the normal distribution, we'll get this one equal to 7.
01:31
14 0 .176, 229 minus here minus 04 minus 1 07 minus 1 4 minus 1 4 2 3 1 then again equal to the 0152 01 and for the question b here we will have the symbol n equal to the 64 now and then one can find the standard division of the sum of the mean x bar...