(a) Calculate a 95% confidence interval for the difference in the mean amount of time that it takes to make a pourover against the mean amount of time it takes to make a red-eye. Can you conclude that making the espresso shot adds a significant amount to the mean time it takes for the preparation? (b) State all of the assumptions that are needed to calculate this confidence interval. EC Show that vS/o² is a pivotal quantity for the population variance of coffee preparation times assumed to be common to both populations, where S? is the pooled sample variance, v is an appropriate number of degrees of freedom, and o? is the unknown population variance. Use the pivotal method to obtain a 90% confidence interval on o?.

Find the value of​ n(A∪​B) if n(A)=3​, n(B)=8 and​ n(A∩B)=2. help please

DO ALL PASRT PLEASE!!!!!!!!!!!

Can I use another question to have the part(d) answered?

must solve all parts for upvote

Travis's carpet has an area of 180 square feet. He hires the CarpetPro carpet cleaning service, which is able to clean 9 square feet of his carpet every minute. Therefore, in the first minute, CarpetPro is able to clean 9 square feet of Travis's carpet (leaving 171 square feet remaining to be cleaned). In the second minute, the cleaner is again able to clean 9 square feet of carpet (leaving 162 square feet to be cleaned), etc. Which of the following functions expresses the number of square feet that still remain to be cleaned after t minutes from the time that the carpet cleaner began cleaning this carpet.   A(t)=180−0.9t A(t)=180(0.1)t A(t)=180(0.9t) A(t)=180−9t A(t)=180−0.1t