in this file : 3.9. Population variance known, z-score_exercise_solution.xlsx https://www.filepicker.io/api/file/wTJ2o2jMRpOgGxTsuPjR the following equations missing parenthesis when calculating confidence interval : =E15-E17*E19 =E15+E17*E19 it should be : =E15-(E17*E19) =E15+(E17*E19)

Hi Hamada, Thanks for reaching out. When you have a mathematical equation or a formula in Excel, multiplication and division are prioritized. Therefore, even without the brackets, E17*E19 will be executed before the plus/minus sign. Best,The 365 Team

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Hamada Abdo

Last answered:

27 Mar 2020

Posted on:

26 Mar 2020

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365 Team

Posted on:

27 Mar 2020

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