00:01
Assuming normal distribution, i find the following probabilities.
00:05
We're to round the values of z to two decimal places and round your answers to four decimal places.
00:12
So the first one is p x p x less than 20 and this is less than 25 and the standard deviation is 4.
00:30
We're to enter the probability rounded to four decimal places.
00:33
So to do this, given that the mean is 25 and standard deviation is 4 and it's going to be p x less than 22 is equal to p x minus the mean divided by the standard deviation less than 22 minus 25 less than divided by 4 and this will be p is equals p open bracket z less than minus 0 .75.
01:05
Using the z table, the probability will be 0 .2266.
01:11
The second question which is p x greater than or equal to 50.
01:18
The mean is equal to 40 and the standard deviation is equals 8.
01:25
To find this one, it will be p x greater than 50 equal to 1 minus p x less than 50.
01:37
So 1 minus p x minus the mean divided by the standard deviation divided by 50 minus 40 divided by 8.
01:49
This will be 1 minus p z less than 1 .25.
01:55
Using the z table, this should be 1 minus 0 .8944 which is equal to 0 .1056...