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Question
Math
Posted 7 months ago

According to a large poll in a previous year, about 80%80 \% of homes in a certain county had access to high-speed internet. Market researchers wondered if that proportion had changed, so they took a random sample of 64 homes from that county and found that 48 of them had access to highspeed internet.

They want to use this sample data to test H0:p=0.8H_{0}: p=0.8 versus Ha:p0.8H_{\mathrm{a}}: p \neq 0.8, where pp is the proportion of homes in this county with high-speed internet access.

Assuming that the conditions for inference have been met, calculate the test statistic for their significance test.
You may round to two decimal places.
z=
z=
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Answer from Sia
Posted 7 months ago
Solution by Steps
step 1
Calculate the sample proportion ( p^\hat{p} ) by dividing the number of homes with high-speed internet by the total number of homes sampled
step 2
p^=4864\hat{p} = \frac{48}{64}
step 3
Simplify the sample proportion: p^=0.75\hat{p} = 0.75
step 4
Calculate the standard error (SE) using the null hypothesis proportion (p0p_0) and the sample size (nn): SE=p0(1p0)nSE = \sqrt{\frac{p_0(1-p_0)}{n}}
step 5
SE=0.8(10.8)64SE = \sqrt{\frac{0.8(1-0.8)}{64}}
step 6
Simplify the standard error: SE=0.8×0.264=0.1664=0.0025=0.05SE = \sqrt{\frac{0.8 \times 0.2}{64}} = \sqrt{\frac{0.16}{64}} = \sqrt{0.0025} = 0.05
step 7
Calculate the test statistic (zz) using the sample proportion (p^\hat{p}), the null hypothesis proportion (p0p_0), and the standard error (SE): z=p^p0SEz = \frac{\hat{p} - p_0}{SE}
step 8
z=0.750.80.05z = \frac{0.75 - 0.8}{0.05}
step 9
Simplify the test statistic: z=0.050.05=1z = \frac{-0.05}{0.05} = -1
Answer
The test statistic (zz) for this significance test is -1.00 (rounded to two decimal places).
Key Concept
Hypothesis Testing and Test Statistic Calculation
Explanation
The test statistic in hypothesis testing measures how far the sample proportion is from the null hypothesis proportion, in standard error units. It is used to determine whether to reject the null hypothesis. In this case, the test statistic helps us understand if the proportion of homes with high-speed internet access has significantly changed from the previous year's proportion of 0.8.

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