# Homework Help: Simple question: 1/3pi(2h/3)^2 * h ?

1. Nov 10, 2012

### nukeman

Simple question: 1/3pi(2h/3)^2 * h ???

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

Can someone please refresh me on the steps:

1/3∏(2h/3)^2 * h

HOW does that turn into:

4∏/27 * h^3

???

2. Relevant equations

3. The attempt at a solution

2. Nov 10, 2012

### SammyS

Staff Emeritus
Re: Simple question: 1/3pi(2h/3)^2 * h ???

What is (2h/3)2 ?

3. Nov 10, 2012

### nukeman

Re: Simple question: 1/3pi(2h/3)^2 * h ???

4h/9

4. Nov 11, 2012

### SammyS

Staff Emeritus
Re: Simple question: 1/3pi(2h/3)^2 * h ???

Why didn't you square the h ?

5. Nov 11, 2012

### Staff: Mentor

Re: Simple question: 1/3pi(2h/3)^2 * h ???

There is a lazy convention which unfortunately has been granted some legitimacy, where some people interpret your line of text to be something different to how most see it.

In your problem, since we know the answer we are working towards, we can work backwards to reveal what is intended, then proceed forwards and solve it.

To leave no doubt in anyone's mind, it is recommended that you be generous with the use of parentheses when forming expressions in text, e.g. write it as (1/3)∏(2h/3)^2 * h when that is what is intended.

Or, if you can find a genuine fraction character, you can use it to eliminate ambiguity, e.g., ⅓∏(2h/3)^2 * h

I have labored the point simply because some people interpret 1/3∏(2h/3)^2 to have an equivalence with
1/(3∏(2h/3)^2), but for your question such an interpretation does not lead to the given answer (so that is the only evidence we have that it is not the interpretation intended here).