Problema Solution

A box has a volume of 570cm3 and a surface area of 478cm2 . What are the length, width, and height of the box?

Answer provided by our tutors

let


l = the length

w = the width

h = the height


the volume of the box V = length*width*height


l*w*h = 570


the area of the surface A = 2wl + 2hl + 2lw


2wl + 2hl + 2lw = 478 divide both sides by 2


wl + hl + lw = 239


we have 2 equation and 3 variables follows there are infinitely many possible solutions.


We will find one possible solution using trials:


since 570 = 2*3*5*19 lets assume that h = 5 then we have


5lw = 570 divide both side by 5


lw = 570/5


lw = 114


and also for wl + hl + lw = 239 and h = 5 we get


5(l + w) + lw = 239


plug lw = 114 into the last equation


5(l + w) + 114 = 239


l + w = (239 - 114)/5


l + w = 25


l = 25 - w


if we plug l = 25 - w into lw = 114 we get


(25 - w)w = 114


by solving we find


w1 = 19


w2 = 6


click here to see the step by step solution of the equation


Click to see all the steps



for w1 = 19


l1 = 25 - 19 = 6


for w2 = 6


l2 = 15 - 6 = 19


since length >= width we found the following dimensions of the box


height = 5

width = 6

length = 19


indeed V = 5*6*19 = 520 and A = 2(5*6 + 5*19 + 6*19) = 478.