The burning rates of two different solid-fuel propellants employed in aircrew escape systems are being studied. It is known that both propellants have approximately same standard deviation of burning rate, that is σ1=σ2=3 centimeters each second. Two random samples of n1=20 and n2=20 specimens are tested, the sample mean burning rates are x bar 1=18 centimeters each second and x-bar2=24 centimeters per second.
a) Test hypothesis that both propellants have the same mean burning rate. Use α=0.05. What is the P value?
b) Make a 95% confidence interval on difference in means μ1-μ2. What is the practical meaning of this interval.