Solution :
The sample proportion 
= 0.024
<u>90% confidence interval </u>
The standard deviation = 
= 
= 0.00484
z = 1.645 for 90% CI
Upper band = 0.024 + (0.00484 x 1.645 ) = 0.03196
Lower band = 0.024 - (0.00484 x 1.645 ) = 0.01603
Therefore, the 90% CI is (0.016, 0.032)
<u />
<u>99% confidence interval </u>
z = 2.576 for 99% CI
Upper band = 0.024 + (2.576 x 0.00484 ) = 0.0365
Lower band = 0.024 - (2.576 x 0.00484 ) = -0.0115
Therefore, the 99% CI is (0.0115, 0.0365)