Fun tests on BBC

[jennyp]

Hey,

I just did a couple of fun quizzes the BBC has up on their magazine Website. They're not as challenging as the ones put out by the folks at ETS, but they're a fun diversion from Power Prep.

Math: http://news.bbc.co.uk/1/hi/magazine/4263590.stm

English: http://news.bbc.co.uk/1/hi/magazine/4246472.stm

By the way, the one question I got wrong on the maths was 18. It has something to do with statistics, but I had no idea how to approach it...anyone know what's going on here?

Cheers, jennyp

[cridamour]

Hey, thanks for the links, Jen!

[raghuveer_v]

QUESTION 18

A company employs 400 workers. Of these 125 people are aged from 40 to 50. A stratified sample of 50 is planned. What number of people should be sampled from the above age group, to the nearest number?

1. 12
2. 16
3. 18
4. 22

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Here 400 is the 'population size' and 50 is the 'sample size'.

For any statistical study to be valid, the sample should be "representative"

i.e., it should represent the distribution of various parameters (as closely as possible) of the original poulation from which it is drawn.

Here the parameter is Age.

The sample should have the same proportion of people aged 40-50 as the original population.

Thus ... if X people out of the sample of 50 are aged 40 to 50,

X / 50 = 125 / 400

X = 15.625 = approx. 16

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Answer: 2. 16

Hope that helps.

[jennyp]

I see,

That totally helps! Thanks a ton, Raghuveer.