Can someone help me with this stratifield sampling question please
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Can someone help me with this stratifield sampling question please

[From: ] [author: ] [Date: 11-04-29] [Hit: ]
where x is the percentage you are looking for.Now, you now that your sample isnt the whole population, but just 50 people.But the percentage of each group MUST be the same than population!!......
Male adults-310
Female adults-240
Male children-125
Female children-65
I added all those together and I got 767

The size of the sample is 50
work out the number of male adults that should be in the sample

I got the answer 40 :\ but I don't think it is right
please help please :(
Thank you!

-
Male adults-310
Female adults-240
Male children-125
Female children-65

These add to 740.

We want the same proportion of male adults in the population as in the sample

The proportion is 310/740

So the number of male adults needed for a stratified sample is:

310/740 x 50 = 20.945 which is about 21 male adults.

-
it is a problem about probability:

You have 310 male adults in your population (that is the sum of the whole number of people): you have to transform that in a percentage:
how much is the percentage of male adults in a population of 767 people?
To solve it you have to solve this equation:
310=x*760
where x is the percentage you are looking for.

Now, you now that your sample isnt the whole population, but just 50 people.
But the percentage of each group MUST be the same than population!!!!!!!!!!!!!!!!!!!!!!
So, the percentage of male adults is again x.

So, the number of male adults in a percentage of x for a sample equal to 50 is:
y=x*50

(you expect to find a number a bit less than 25 because 310 is a bit less than the half of 767)

I hope my english is understandable..I am sorry, I am not english native :)
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