Question

In 2008, there were 507 children in Arizona out of 32,601 who were diagnosed with Autism Spectrum Disorder (ASD) ("Autism and developmental," 2008). Find the proportion of ASD in Arizona with a confidence level of 99%.

Answer 1

Answer:

The 99% confidence interval for the proportion of ASD in Arizona is (0.014, 0.018).

Step-by-step explanation:

The information provided is as follows:

$x=507\\n=32601\\\text{Confidence level }=99\%$

The sample proportion is:

$\hat p=\frac{x}{n}=\frac{507}{32601}=0.016$

The critical value of z for 99% confidence level is, z = 2.56.

Compute the 99% confidence interval for the proportion of ASD in Arizona as follows:

$CI=\hat p\pm z_{\alpha/2}\cdot\sqrt{\frac{\hat p(1-\hat p)}{n}}$

    $=0.016\pm 2.58\cdot\sqrt{\frac{0.016(1-0.016)}{32601}}\\\\=0.016\pm 0.0018\\\\=(0.0142, 0.0178)\\\\\approx (0.014, 0.018)$

Thus, the 99% confidence interval for the proportion of ASD in Arizona is (0.014, 0.018).