Adam measured a line to be 6.4 inches long. If the actual length of the line is 6.7 inches, then what was the percent error of the measurement, to the nearest tenth of a percent?

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