00:02
In this lesson, in this lesson we have the mean score as 81 .52 and the standard deviation as 9 .2.
00:19
So we are looking for the probability of a score that is less than 75.
00:27
So what we'll do is that we'll find a z value of that.
00:31
So 75 minus 81.
00:38
52 all over 9 .2 because the z is then the score you are looking for minus the mean all over the standard deviation okay so here we have negative 5 point negative 6 .52 all over 9 .2 and that gives us negative 0 .71 so the z or the probability of z that is less than negative 0 .7 is negative 0 .71 so this is 0 .7 and 1 that is here we have negative 0 .7 than 0 .01 okay so that is 0 .2 3rd now to trade the smart places the next one that we look at is a probability of a score that is between 85 and 92 okay so let's look for the z values of 85 and 92 so that gives us 0 .38 then a z value for 92 is also 1 .14.
03:01
Okay, so this becomes 0 .38.
03:08
So z that is less than 0 .38, then z that is greater than 1 .14.
03:18
So that becomes probability of z less than 1 .14 minus probability of z that is less than 1 .14 minus probability of z.
03:28
That is less than 0 .38 okay so from the table we have 0 .87 -286 minus 0 .4 0 .64803 and that gives us 0 .25.
04:00
Okay so fine then let's go over how we found z less than 0 .0 less than 0 .14.
04:14
So z less than 1 .14.
04:27
Okay, we have both negatives.
04:30
All right.
04:34
So look for z that is 1 .4...