Simple random sample: Every member and set of members has an equal chance of being included in the sample. Random samples are usually fairly representative since they don't favor certain members.
Because if you flip it 20 times and it lands on tails 6 times, you just have to add 20+20 6+6 so then it's 40 flips and 12 tails. 60 times and 18 tails 8p times and 24 tails.
The answer is 12 but the way you get it is you subtract 400 from 1000 which gives you 600 then you divide 600 by 50 to get 12. So it looks like this 1000-400= 600, 600/50=12. Hope this helps. :)
