00:01
Once again, welcome to new problem when distributions, when distributions are normal, then what tends to happen is that these distributions have a bell shape, meaning that for the most part, a lot of the data is centered in the middle.
00:27
So a lot of the data is centered in the middle, so it's a normal distribution, and it's bell shape.
00:35
And a logarithm, a log rhythm is a type of a numbering system that's the inverse of an exponential function.
00:48
So for example, if this is the graph that reflects an exponential function, f -fx equals, to e to the x, then if we wanted to have an inverse function, this is the inverse of the function and this is a log function.
01:12
So for this f of x would be ln of x, which is a log function.
01:17
That's a logarithmic function.
01:21
So we do have what we call a log normal.
01:28
Distribution, we do have a log normal distribution.
01:33
And a log normal distribution, first of all, it's a continuous distribution for the most part.
01:46
And then it's a probability distribution, meaning that it involves random variables whose logs have a normal distribution.
02:18
So the logs of these random variables do have what we call a normal distribution.
02:28
So coming back to this particular problem, assume we have a line.
02:35
Lifetime distributions.
02:39
So assume we have lifetime distributions and this distribution with like high -speed recordable optical discs and we assume we assume that these follow normal distributions.
03:09
So the assumption is that these ones are following normal distributions and we have moon of 2 .5 and a standard deviation of 0 .5 weeks so the main is 2 .5 weeks and the standard deviation is 2 .5 weeks and 2 .5 weeks and assuming that 98 % of the disks fail before a's year weeks, then a zero weeks.
04:23
So they fail before a zero weeks.
04:28
Then determine the value, determine the value of a zero.
04:38
You want to determine the value for a0.
04:41
We do have the numbers in the table.
04:44
We do have the numbers in the table.
04:47
So 30 .05, 38 .45, 36 .65.
04:57
35 .65 .3333 .93 .93 .93 .93...