Question

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.

Answer 1

n1= 158, xbar=67.5 and =17.81

n2= 179, ybar= 55.2 and = 19.32

Since population standard deviation is known so we will use Z critical value.

Z critical value for 0.98 confidence level 2.33

98% confidence level is

is 98% confidence interval