00:01
Hello students, we are going to write here sample mean is 20 and population standard deviation is 7, which sample size is 130.
00:09
What is the probability that sample of 130 study smokers spend between 19 and 21? so we are going to write here for this.
00:18
We need to write normal distribution.
00:22
If i write here for this, this must be solved.
00:26
According to normal distribution, in the normal distribution, all these are all these.
00:31
Random variables are distributed amongst well -shaped curve right -inside area is 0 .5, left -inside areas 0 .5.
00:40
It means that area is symmetric about y -axis and total area under normal distribution curve is 1.
00:48
So if i write here, z -score attribute is x minus mu divided by sigma, we are going to write here for this.
00:59
This must be x minus mu divided by sigma.
01:02
So here total number of sample size is given.
01:05
So we need to write here mu x and sigma x.
01:08
So sample mean is can be written equivalent to our mean and this must be equivalent to sigma divided by under root of n.
01:17
So this is x minus.
01:19
So jad 1 value is x value x value is 19 minus 20 divided by sigma sigma is 7 and this is 1 under root of 130 so this must be minus of under root of 130 so let's erase this to make it more clear we are going to write here for this this must be written as minus 1 .63 so let's say what would be our jett2 value which will be 21 minus 20 so let's say what would be our jett2 value which will be 21 minus 20 so let's say what would be our z 2.
01:57
So let's say what would be our z 2.
01:57
Let's erase this to make it more clear...