Task: Question Answering
Input (English): Question: We want to compare the means of two populations that follow normal distributions and have the same variance. We take two samples of size n1 and n2. When constructing a confidence interval we will have to calculate a value t for a Student's T distribution with: 
 Options:  <1> 2 degrees of freedom. <2> n1 + n2 - 2 degrees of freedom. <3> (n1 + n2) - 1 degrees of freedom. <4> (n1 x n2) / 2 degrees of freedom. <5> Degrees of freedom calculated with the formula of Welch or Smith-Satterwhite.
Output (English): 2