The z or t score to be used is (0.422,0.978)
How to find the critical value ?
Critical probability (p*) = 1 - (Alpha / 2), where Alpha is equal to 1 - (the confidence level / 100), is the unit statisticians use to determine the margin of error within a set of data in statistics.
The critical value for α = 0.13 is
The corresponding confidence interval is computed as shown below
CI = (0.422, 0.978)
0.422< mu1 - mu 2 < 0.978
To learn more about finding the critical value from the given link
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