Answer: A. z = -2.57
Step-by-step explanation:
Let p be the population proportion of people polled favor the incumbent.
As per given , we have
Sample size : n= 1030
sample proportion :
Test statistic for proportion :
Hence, the test statistic is z = -2.57 .
Thus , the correct answer is A. z = -2.57 .
Answer:
The margin of error is of
Step-by-step explanation:
We have the standard deviation for the sample. So the T-distribution is used to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 10 - 1 = 9
95% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 9 degrees of freedom(y-axis) and a confidence level of . So we have T = 2.262
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.