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
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.