you buy x packs of pencils, twice as many packs of erasers, and three times as many tolls of tape. write an expression in the simple form for the total amount of money spent

The brain volumes (cm cubed) of 50 brains vary from a low of 904 cm cubed to a high of 1488 cm cubed. use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 175.5 cm cubed, assuming the estimate is accurate if it is within 15 cm cubed