Question

In a college population of 10,000 people, suppose you want to randomly pick a sample of 1000 for a survey. For any particular sample of 1000, if you are sampling with replacement,
what is the chance of picking the first person .
 what is the chance of picking a different second person . and lastly, what is
 the chance of picking the same person again. please help me, i think i can do the first one.

Answer 1

"what is the chance of picking the first person" doesn't really make sense, unless the idea is with a population of 10,000, on the first selection, what are the chances of picking any particular person? In that case, it would just be 1/10,000

Answer 2

it does make sense, wikipedia has an answer, but dont cheat

Answer 3

and no, the answer should be .1

Answer 4

well, I think wikipedia should be trusted implicitly. Why do you question it? Submit to Wikipedia and enjoy crowd-sourced peace.

Answer 5

here is the link of wikipedia http://en.wikipedia.org/wiki/Simple_random_sample

Answer 6

well it also agrees with my book

Answer 7

scroll down to the example

Answer 8

here is my book excerpt

Answer 9

, in a college population of 10,000 people, suppose you want to randomly pick a sample of 1000
for a survey. For any particular sample of 1000, if you are sampling with replacement,
the chance of picking the first person is 1000 out of 10,000 (0.1000);
the chance of picking a different second person for this sample is 999 out of 10,000 (0.0999);
the chance of picking the same person again is 1 out of 10,000 (very low).
If you are sampling without replacement,
the chance of picking the first person for any particular sample is 1000 out of 10,000 (0.1000);
the chance of picking a different second person is 999 out of 9,999 (0.0999);
you do not replace the first person before picking the next person.
Compare the fractions 999/10,000 and 999/9,999. For accuracy, carry the decimal answers to 4 place decimals.
To 4 decimal places, these numbers are equivalent (0.0999).

Answer 10

i dont really understand the chance of picking a different second person

Answer 11

i agree that these questions are not very clear

Answer 12

here is wikipedia's wording
Let us assume you had a school with 1000 students, divided equally into boys and girls, and you wanted to select 100 of them for further study. You might put all their names in a bucket and then pull 100 names out. Not only does each person have an equal chance of being selected, we can also easily calculate the probability of a given person being chosen, since we know the sample size (n) and the population (N):

1. In the case that any given person can only be selected once ie. after selection person is removed from the selection pool (basic probability):

Answer 13

sleep beckons, sorry for my attitude... you're doing good work here, and I honestly applaud it... helping, generously, is the best.

and omg, that was quite a complete solution just now... extremely well done!

Answer 14

heh, well that was copy and paste. thanks for trying :)

Answer 15

i think , whats the probability of a person being selected *given* 100 people were selected

Answer 16

well ill keep working on it , cya