Question

Is this a one- or two tailed test? An LU professor is interested in whether there is a difference between undergraduate students and graduate students in the amount of time spent praying each day. The professor gathers information from random samples of undergraduate and graduate students on the LU campus. The amount of time praying is normally distributed and is measured on an interval/ratio scale.

Answer 1

The question is "whether there is a difference between...".

And the difference exists in two cases:
- undergraduate students spend more time praying eachday than graduate students
- graduate students spend more time praying each daythan undergraduate students
So, the difference d between times spent praying each dayfor undergraduate students and graduate students can be < 0 or > 0 for
the difference to exist.
Thus professor should use two-tailed test.