Select the polynomial that can be factored as (3x + 9)(3x - 9) a. 9x^2 - 27x - 81 b. 9x^2 + 54x -81 c. 9x^2 - 81 d. 9x^2 - 54x - 81

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