Is 12 posters for 36 students equivalent to 21 posters to 63 student

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

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

Which number line correctly shows 0.8 + 0.3?