SOLUTION: A recent report indicated that 67% of teens 12 to 19 play a video game online at least once a week. How large of a sample would a researcher need to estimate the true proportion of

Question 1069519: A recent report indicated that 67% of teens 12 to 19 play a video game online at least once a week. How large of a sample would a researcher need to estimate the true proportion of teens 12 to 19 who play a video game online at least once a week within 3% with a 95% confidence level?
a) 844
b) 4489
c) 944
d) 4144
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
half of the interval for a one sample proportion is z(0.975)sqrt{p*(1-p)/n}, and it equals .03
.03=1.96*sqrt {(.67)(.33)/n}
square both sides
.0009=3.8416*(.67*.33)/n
.0009n=0.8494 (I would not round but keep it on the calculator unrounded until the end.
divide by .0009
943.75. Round upward to 944.
C.
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