Question: It is taken from a random sample of size n₁ = 16 normal population having an average of 75 and a standard deviation of 8.
In other normal population takes a random sample of size n₂ = 9; this population has a mean of 70 and a standard deviation of 12.
What is the probability of \[{{\bar{X}}_{1}}-{{\bar{X}}_{2}}\] would be greater than four?
What is the probability that \[3.5\le \ {{\bar{X}}_{1}}-{{\bar{X}}_{2}}\le \ 5.5\] ?