some states now allow online gambling. as a marketing manager for a casino, you need to determine the…

some states now allow online gambling. as a marketing manager for a casino, you need to determine the percentage of adults in those states who gamble online. how many adults must you survey in order to be 99% confident that your estimate is in error by no more than five percentage points? complete parts (a) and (b) below. a. assume that nothing is known about the percentage of adults who gamble online. n = (round up to the nearest integer.) b. assume that 17% of all adults gamble online. n = (round up to the nearest integer.)

some states now allow online gambling. as a marketing manager for a casino, you need to determine the percentage of adults in those states who gamble online. how many adults must you survey in order to be 99% confident that your estimate is in error by no more than five percentage points? complete parts (a) and (b) below. a. assume that nothing is known about the percentage of adults who gamble online. n = (round up to the nearest integer.) b. assume that 17% of all adults gamble online. n = (round up to the nearest integer.)

Answer

Explanation:

Step1: Identify the confidence - level and margin of error

For a 99% confidence level, the z - score $z_{\alpha/2}=2.576$. The margin of error $E = 0.05$.

Step2: Use the formula for sample size when $p$ is unknown

The formula for sample size $n$ when the proportion $p$ is unknown is $n=\frac{z_{\alpha/2}^{2}\times0.25}{E^{2}}$. Substitute $z_{\alpha/2}=2.576$ and $E = 0.05$ into the formula: [ \begin{align*} n&=\frac{(2.576)^{2}\times0.25}{(0.05)^{2}}\ &=\frac{6.635776\times0.25}{0.0025}\ &=\frac{1.658944}{0.0025}\ & = 663.5776 \end{align*} ] Round up to the nearest integer, so $n = 664$.

Step3: Use the formula for sample size when $p$ is known

The formula for sample size $n$ when the proportion $p$ is known is $n=\frac{z_{\alpha/2}^{2}\times p(1 - p)}{E^{2}}$. Given $p = 0.17$, then $1-p=0.83$, $z_{\alpha/2}=2.576$ and $E = 0.05$. [ \begin{align*} n&=\frac{(2.576)^{2}\times0.17\times0.83}{(0.05)^{2}}\ &=\frac{6.635776\times0.1411}{0.0025}\ &=\frac{0.936308}{0.0025}\ &=374.5232 \end{align*} ] Round up to the nearest integer, so $n = 375$.

Answer:

a. 664 b. 375