# Word problem polynomial f(x) help

1. Sep 24, 2011

### Nelo

1. The problem statement, all variables and given/known data

2 People build a sandcastle of 36cm by 48cm by 60cm. Later they learn that the box will be smaller; a certain amount will be taken off each of the length width and height

2. Relevant equations

3. The attempt at a solution

a) write a p(x)
> (36-x) (48-x) (60-x) , also x intercepts if (-x+36) = -(x-36) etc

c) the amount of sand in the boc will be 3/5 of the amount in the design) , so i multiplied the l*w*h and then multiplied it by 3/5 and got the answer of 103,680 *3/5 = 62,208

d) How much was taken off each dimension? ( HOW DO I SOLVE THIS?) anyone? steps plz

2. Sep 24, 2011

### Nelo

any1?

3. Sep 24, 2011

### epenguin

Before the answer we'd need a question.

4. Sep 24, 2011

### Staff: Mentor

What do you mean, "write a p(x)" - A function that represents what?

Please give us the exact problem statement.

5. Sep 24, 2011

### eumyang

Looks like you'll need to take p(x) and set it equal to 62,208:
(36 - x)(48 - x)(60 - x) = 62,208

However, unless you're allowed to solve it graphically using a graphing calculator, I'm not sure you can solve it algebraically (unless you know the cubic formula).

6. Sep 24, 2011

### Nelo

Um, Idk, the answer booklet says "approxmiately 9.28" , but yes im on d) and that is the function...

7. Sep 24, 2011

### Staff: Mentor

If each dimension is reduced by 7.15 you get very close to the desired smaller volume.

8. Sep 25, 2011

### eumyang

Hmm, then either the answer booklet has a typo or you copied the problem wrong. I got the same answer that NascentOxygen got.