While baking, Evan discovered a recipe that required 1/2 cups of walnuts for every 2 1/4 cups of flour. How many cups of walnuts will he need for 4 cups of flour?(redo again, please give me good explanation and understandable steps)

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?