In a recent poll, 600 people were asked if they liked soccer,
and 10% said they did. Based on this, construct a 90% confidence
interval for the true population proportion of people who like
soccer.
As in the reading, in your calculations:
--Use z = 1.645 for a 90% confidence interval
--Use z = 2 for a 95% confidence interval
--Use z = 2.576 for a 99% confidence interval.
Give your answers as decimals, to 4 decimal places.
[________, ________]
Solution :
Given that,
Point estimate = sample proportion = = 0.10
1 - = 1 - 0.10 = 0.90
Z/2 = Z0.05 = 1.645
Margin of error = E = Z / 2 * (( * (1 - )) / n)
= 1.645 (((0.10 * 0.90) / 600)
= 0.0201
A 90% confidence interval for population proportion p is ,
± E
= 0.10 ± 0.0201
= ( 0.0799, 0.1201 )
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