4. These are two hypotheses with the two samples drawn independently from 2 normally distributed distributions.

• H_o: ₁- ₂= 0
• H_a: ₁- ₂not equal to 0
  

1 = 57 (Mean 1) 2 = 63 (Mean 2) 513= 11.5 (Sigma squared 1) 623= 15.2 (Sigma squared 2) "= 20 (Sample size) 21=20 (Sample size)