Critical values for quick reference during this activity Confidence level Critical value 0.90 2* = 1.645 0.95 2* = 1.960 0.99 2* = 2.576 424242 2628466.qx3zay7 Jump to level 1 The manager of a bookstore with a coffee shop wants to know the proportion of customers that come into the store because of the coffee shop. A random sample of 75 customers was polled. Use Sheet 1 of the Excel file linked above to calculate p and the 95% confidence interval. P = EX: 1.234 + Upper bound for 95% confidence interval = Ex: 1.234 Lower bound for 95% confidence interval = The manager can say with 95% confidence that the true population proportion of the customers that come into the store because of the coffee shop is in the interval [ Ex: 1.234], A