Help!! (Question in picture)

Restrictions on f(x) = 1/x+5 and g(x) = x-2

Explain how you can use the associative property to evaluate (7x50)x4.

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