Math Help - Cuboid

1. Cuboid

If each side of a cuboid is doubled,its volume is
(a)doubled
(b)becomes 4 times
(c)becomes 6 times
(d)becomes 8 times

2. Originally Posted by devi
If each side of a cuboid is doubled,its volume is
(a)doubled
(b)becomes 4 times
(c)becomes 6 times
(d)becomes 6 times
Let $x$ be the side length of a cuboid.

the volume is given by:

$V = x^3$

now change $x$ to $2x$. what happens to $V$? how many times larger does it become?

3. Originally Posted by devi
If each side of a cuboid is doubled,its volume is
(a)doubled
(b)becomes 4 times
(c)becomes 6 times
(d)becomes 6 times
d) becomes 6 times as posted is a typo. It should have been becomes 8 times.

Original volume = a*b*c = abc
When each side is doubled, new volume = (2a)(2b)(2c) = 8abc.

4. Originally Posted by ticbol
d) becomes 6 times as posted is a typo. It should have been becomes 8 times.

Original volume = a*b*c = abc
When each side is doubled, new volume = (2a)(2b)(2c) = 8abc.
Yes it is a typo.But the answer was doubled.

5. Originally Posted by devi
Yes it is a typo.But the answer was doubled.
You mean the answer is a)?
Cannot be.

A dictionanary says a cuboid is a rectangular parallelepiped. So it looks like any box of six rectangular faces. (A square is also a rectangular, by the way).
So the volume is length*width*height.
If all those 3 dimensions are doubled, then the original volume is doubled only according to your book?