00:01
Hi, i'm david and i'm here.
00:03
Now let me bring up the question here.
00:06
In the question here we are going to discuss about the normal distribution.
00:11
Let me remind you that if the x then followed by the normal, with the mean the standard deviation, if we tell the x we manage the mean of a standard deviation, we obtain the standard normal.
00:22
In the question here we have the amount spent x it will follow by the normal, when the mean it will equal to the value.
00:30
45 and the standard division equal to the 11 and the manager wishes to give a reward to the people who spend the top 20 % so we need to find a cutoff so i want to find the probability of the x greater equal to some cutoff c i don't know and it will equal to the 20 % now to find the volume of the c i need to confirm the x into the z to do it i need to apply the formula here so i will turn the cutoff c and minus the means rather the standard deviation 20 % equal to the zobon 2.
01:07
The next time we need to convert the z1 2 into the form of probability.
01:12
To do it, i need to bring up the z table and i put it on the right here.
01:18
Notice the standard table i bring here, it has the negative g score with the probability on the left tail...