a survey of 225 students showed the mean number of hours spent studying per week was 20.6 and the standard…

a survey of 225 students showed the mean number of hours spent studying per week was 20.6 and the standard deviation was 2.7. assuming a 90% confidence level, the margin of error is approximately 0.3. which of the following gives the confidence interval? between 0.07 and 0.13 between 2.4 and 3.1 between 20.3 and 20.9

a survey of 225 students showed the mean number of hours spent studying per week was 20.6 and the standard deviation was 2.7. assuming a 90% confidence level, the margin of error is approximately 0.3. which of the following gives the confidence interval? between 0.07 and 0.13 between 2.4 and 3.1 between 20.3 and 20.9

Answer

Explanation:

Step1: Recall confidence - interval formula

The confidence - interval formula for a population mean when the population standard deviation is unknown (but sample size is large, $n\geq30$) is $\bar{x}\pm E$, where $\bar{x}$ is the sample mean and $E$ is the margin of error.

Step2: Identify given values

We are given that $\bar{x} = 20.6$ and $E=0.3$.

Step3: Calculate the lower and upper bounds

The lower bound is $\bar{x}-E=20.6 - 0.3=20.3$. The upper bound is $\bar{x}+E=20.6 + 0.3=20.9$.

Answer:

between 20.3 and 20.9