I have create a dynamic bell curve with Excel using Scroll Bar. You can check it here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jzLGWoxPL8M.html
I do not know what you mean by truncated. But here is a video from my analytics class that shows how to create various distribution random variables, including normal: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7NNtUs5xAkw.html
I have create a dynamic bell curve with Excel using Scroll Bar. You can check it here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jzLGWoxPL8M.html
That is not the formula that was typed. Mean - 4 standard deviations = 74-10*4 = 34 = start value to plot all the way down to 4 SD. Maybe you need glasses lol