Is it about statistics?

Question

Hi, not sure it's the right place to ask. Anyway, I searched online & ended up in confused with this one:

Let's take 1 question as an example:

The drying rate in an industrial process is dependent on many factors and varies according to the following distribution.

 Minutes Relative Frequency
 3       0.22
 4       0.36
 5       0.28
 6       0.10
 7       0.04

Using these random numbers, simulate the drying time for 5 processes: 0.13; 0.09; 0.19; 0.81; and 0.12.

If anyone of u guys know how to solve it or what book I should read to solve this kind of problem, please let me know (I do have some basic understanding of probability & statistic but really don't understand what the question).

Answer 1

This is a probability question. Any introductory probability textbook should lead you the right way. What you are given here is a probability mass function (note the values add up to 1)..

You can read the numbers this way:

the likelihood it takes the drying time 3 minutes is 0.22 the likelihood it takes the drying time 4 minutes is 0.36 the likelihood it takes the drying time 5 minutes is 0.28 the likelihood it takes the drying time 6 minutes is 0.10 the likelihood it takes the drying time 7 minutes is 0.04

The question is a little counter intuitive (hint: think about the 0-1 interval for your 'random' numbers, and each 'chunk' of that interval being the length one of the PMF values).

As for a book, you could try (but really, any intro prob. book would work): D. P. Bertsekas and J. N. Tsitsiklis, Introduction to Probability, 2nd Edition, Athena-Scientific, Belmont, Mass., 2008.