00:01
We have been given some population data.
00:03
The population mean length of unemployment, so mu, is 16 weeks with a standard deviation sigma of 2 .9 weeks.
00:11
And in part a we want probability a value from this distribution, so x, is greater than 15 .4.
00:18
So random observation from the population.
00:21
Okay so immediately we have a problem here.
00:23
We have not been told the shape of this distribution but it wants an answer.
00:28
So considering part b is going to involve the normal distribution i will assume that the population is normally distributed.
00:38
Otherwise we're a bit stuck.
00:40
Strictly the answer here should be i can't answer this question because i don't know the shape of population.
00:44
We will assume it is normal.
00:47
So assume normal.
00:50
We don't need this assumption for part b which we'll get to shortly.
00:54
So 15 .4 is below the mean.
00:57
We want greater than, so we want the area to the right.
01:01
To find this area you need something with the normal distribution built in.
01:04
That could be software like excel or r.
01:07
I'm going to use my ti -84 calculator with the normal cdf function.
01:14
This has four inputs.
01:16
Lower bound, upper bound, mean and standard deviation...