Dot plots are often used for what 2 sets of data

On average, how many more hits will he get when he bats 100 times at home during the day as opposed to 100 times away at night?

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?

What is the product? a-3/15a × 5/a-3