Randomly selecting

[BLACKCATT]

Hi everyone,
i have my first CORE sac in a few weeks and I've started to look at some practice sacs. A question that i don't understand is that they ask you randomly select the data. Could someone please explain to me what this is and how it is done.
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[Kuchiki]

I'm not sure if this is what you mean, but on your CAS calculator, if you press menu -> 5: Probability -> 4: Random -> 2: Integer, and then type in (*minimum*, *maximum*, *number of results*), it'll randomly choose values for you to use.

For example, if you put in randInt(10,50,5), it'll give you five random numbers between 10 and 50 inclusive, like {19,25,10,48,14}.

[Yacoubb]

A random sample is when you withdraw a sample of participants from a large population. Random sampling makes sure that all participants have an equal chance of being in the sample & you increase the credibility of your findings because there is no bias.

[Zealous]

Also, it's useful to increase the amount of values you generate.

eg. let's say you have to randomly select 20 values between 1 and 100.
So you should use:

= {98,28,28,13,6,73,2,43,31,98,3,84...}

but there is a chance that you may get duplicates in your answer, so it might be useful to increase the amount of numbers you generate and skip the duplicates, eg.

[BLACKCATT]

Thanks for the replies!
How would you randomly select a consecutive set of data?

[Zealous]

Could you elaborate on what you mean by consecutive set of data?

I think you mean, lets say you have to pick 3 groups of 10 consecutive years from 1960 to 2000.

So you could use this:

(the reason why you stop at 1990 is that 10 consecutive years from that will hit 2000, and that's the maximum value you can have.)

Results to = {1961, 1963, 1981}
So your 3 groups would be:
1961 - 1971, 1963 - 1973 and 1981 - 1991

That's what I think you were asking, although I may be completely off lol.

[BLACKCATT]

That explains it, thanks 

[lala1911]

If you have the Cambridge Essentials Further Mathematics textbook it's explained on pages 84 and 85 on how to generate a simple random selection.
If you have a classpad, you need to determine:
1. The number of random numbers you require
2. The starting integer value
3. The finishing integer value
Assuming you want 20 numbers, the starting number is 1 and the finishing integer value is 99. You would type in randlist(20,1,99)