Determine the number of degrees of freedom for the two-sample t test or CI in each of the following situations. (Round your answers down to the nearest whole number.) (a) m12, n = 15, S₁ = 3.0, S2 = 5.0 S1 23 (b) 31 m = 12, n = 21, S1 = 3.0, 52 = 5.0 (c) m = 12, n = 21, S1 = 2.0, s2 = 5.0 (d) m = 10, n=24, S₁ = 3.0, S₂ = 5.0