The weight of
10,000
identical samples of a substance is
1
pound.
what is the weight of
10
samples?

The correct answer is:

1/1000 of a pound.

Explanation:

We will set up a proportion to solve this.

The first ratio of the proportion comes from our given information.  10,000 samples weigh 1 pound; this gives us the ratio 10,000/1.

The second ratio will be set up in the same fashion; in this case, the number of samples over the number of pounds.  We know we have 10 samples, but an unknown number of pounds; this means we use a variable to represent the number of pounds:

10/x

This makes our proportion

10,000/1 = 10/x

Cross multiplying, we have

10000(x) = 10(1)

10000x = 10

Divide both sides by 10000:

10000x/10000 = 10/10000

x = 10/10000 = 1/1000