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Its worth 10000000 points need asap if you answer correctly ill mark brainliest

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?

Collin did the work to see if 10 is a solution to the equation r/4=2.4