A sample of 800 shoppers reveals that 10.5% of them used a coupon at checkout. Find a 95% confidence interval for the true population proportion. Answer each intermediate question below. Put your answers in the green boxes. Use formulas. A. Find the critical value using Excel B. Find the relevant standard error C. Find the margin of error D. Find the 95% confidence interval (put the lower end in one box and the upper end in the other) A sample of 800 shoppers reveals that 10.5% of them used a coupon at checkout. Find a 95% confidence interval for the true population proportion. Answer each intermediate question below. Put your answers in the green boxes. Use formulas. A. Find the critical value using Excel B. Find the relevant standard error C. Find the margin of error D. Find the 95% confidence interval (put the lower end in one box and the upper end in the other)