In: Statistics and Probability
For this problem, carry at least four digits after the decimal
in your calculations. Answers may vary slightly due to
rounding.
In a random sample of 502 judges, it was found that 275 were
introverts
(b) Find a 99% confidence interval for p. (Round your answers to two decimal places.)
lower limit | |
upper limit |
Solution :
Given that,
n = 502
x = 275
Point estimate = sample proportion = = x / n = 275 /502 = 0.548
1 - = 1 - 0.548 = 0.452
At 99% confidence level
= 1 - 99%
= 1 - 0.99 =0.01
/2
= 0.005
Z/2
= Z0.005 = 2.576
Margin of error = E = Z / 2 * (( * (1 - )) / n)
= 2.576 (((0.548 * 0.452) / 502)
= 0.06
A 99% confidence interval for population proportion p is ,
± E
0.548 ± 0.06
Upper limit = 0.61
Lower limit = 0.49