Answer:
a) There is no evidence to support the claim that there is no difference in mean foam expansion of these two agents.
b) P=0
c) 90% CI
This CI tells us that there is a 90% confidence that the real value of the difference between the means is between this two values. We see that both are negative values, so the value 0 is left out of the interval.
That means we can be almost sure both means don't have the same value, confirming the results of the previous test.
Step-by-step explanation:
The null and alternative hypothesis are:
The significance level is 0.10 and it will be a two-tailed test.
The difference of the sample means is:
As the sample size is equal for both samples, the estimated standard error of the difference between means is calculated as:
Then, the statistic z is:
The P-value (P=0) is much lower than the significance level, so the null hypothesis is rejected. The means are different.
For a 90% confidence interval for the difference of the means, we use a z=1.645.
Then the confidence interval is defined as:
This CI tells us that there is a 90% confidence that the real value of the difference between the means is between this two values. We see that both are negative values, so the value 0 is left out of the interval.
That means we can be almost sure both means don't have the same value.