# Finding the mass of a screw

1. Dec 7, 2006

### Engage

I have been given the masses of 5 cups, each with a different amount of screws inside.
1st cup = 13g
2nd cup = 19g
3rd cup = 8g
4th cup = 26g
5th cup = 38g

I need to find the mass of a single screw.

I was not given any equations or data besides those masses

I have no clue how to approach this, we have not done anything like it before and therefore have no skills to solve this. Please help!

2. Dec 7, 2006

### billiards

first you have to make an assumption: all cups are the same weight and all screws are the same weight.

is there a common difference between these masses?

They're all integers right, so perhaps a screw weighs 1g? There's a mix of even and numbers so screw's can't weigh an even amount. Maybe they all weigh 3g, does that work? 5, 7 etc...?

Just mess around and see what you find, then in your answer explain the uncertainty and put in all the things you think it could be.

3. Dec 7, 2006

### DaveC426913

What is the largest common factor of those numbers? A screw cannot weigh more than that.

4. Dec 7, 2006

### tim_lou

are you given the mass of the cup? if the cups are not massless then there will be a lot of possibilities for answers. and if the mass of the screws are allowed to be non integers, the question will have an infinite numbers of answers.

Last edited: Dec 7, 2006
5. Dec 8, 2006

### DaveC426913

Clearly the answer will have to include some assumptions and some logic to determine the most reasonable value. Given that all the data supplied are integers, I think we can manage to not overcomplicate the problem.

6. Dec 8, 2006

### Engage

Thanks! I finally figured it out.

7. Dec 8, 2006

### Dookos

Could you please share with us how you figured it out? I'm interested in knowing