-16 + 4x^2 = 0
Please help. If possible can I get a step by step ?

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

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

Which angle has the same measure as the dehedral angle formed by the orange face and the purple rectangle