Question

2. A polling company has been hired to estimate the percentage of people who use Twitter among various demographic groups within the U.S. 
 
 The polling company has already surveyed one thousand people within the ages 18-44. This age group makes up about 36.5% of the overall population of the U.S. 
 
 Now the polling company wants to survey people ages 45-64, who make up about 26.4% of the overall population of the U.S. Other things being equal, about how many people should they survey in the 45-64 year old group to achieve a similar level of accuracy in their estimates in both age groups?
 
 
 Answer: _____________ people
 Explain your answer in one sentence: 


Answer 1

Answer : 723 people

Explian : For 36.5% people , the number of people surveyed is 1000, for 26.4% people, the number of people should be surveyed is 1000*26.4 / 36.5 = 723 ( rounded to whole number )

Note : Let x be the number of people surveyed in 45-64 age group

to get similar level of accuracy , sample size should be proportional to population size

thus we get

36.5 : 1000 :: 26.4 : x