Posted by **justme** on Thursday, October 13, 2011 at 6:44pm.

the width of a square-based storage tank is 3m less than its height. The tank has a capacity of 20m^3. If the dimensions are integer values in metres, what are they?

- math -
**Reiny**, Thursday, October 13, 2011 at 7:23pm
each side of base --- x m

height --- x+3

x^2(x+3) = 20

x^3 + 3x^2 = 20

since the solution is to be an integer, try

x=1 , 1 + 3 = 20 , no

x=2, 8 + 3(4) = 20 ,YES

well, that was easy.

base is 2 m by 2, with a height of 5

- math -
**justme**, Thursday, October 13, 2011 at 7:32pm
but its less than 3

- math -
**Reiny**, Thursday, October 13, 2011 at 7:39pm
base is 2 m by 2 m

height is 2+3 = 5 m

volume = 2x2x5 = 20

My answer is correct.

what do you mean by "but its less than 3"

- math -
**justme**, Thursday, October 13, 2011 at 7:56pm
oh nothing , i get it now, thank you :)

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