Question

question 10 of 13 step 1 of 2 a researcher compares the effectiveness of two different instructional methods for teaching anatomy. a sample of 158 students using method 1 produces a testing average of 67.5. a sample of 179 students using method 2 produces a testing average of 55.2. assume the standard deviation is known to be 17.81 for method 1 and 19.32 for method 2. determine the 98% confidence interval for the true difference between testing averages for students using method 1 and students using method 2. step 1 of 2: find the critical value that should be used in constructing the confidence interval. answerhow to enter your answer (opens in new window) 1 point tables keypad keyboard shortcuts

Explanation:

Step1: Identify the confidence level

The confidence level is 98%, so the significance level $\alpha=1 - 0.98=0.02$.

Step2: Determine the two - tailed critical value

For a two - tailed test, we divide $\alpha$ by 2, so $\alpha/2 = 0.01$. We look up the $z$ - value in the standard normal distribution table corresponding to an area of $1-\alpha/2 = 0.99$.
The $z$ - value corresponding to an area of 0.99 in the standard normal distribution table is approximately $z_{\alpha/2}=2.33$.

Answer:

$2.33$